[REL] v1.4.9

# v1.4.9

- fix: correctly capture the scope of arrow functions passed as props

.github/workflows/deploy.yml

@@ -0,0 +1,27 @@
+# This workflow will do a clean install of node dependencies, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+name: Node.js CI
+
+on:
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [12.x, 14.x, 16.x]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: npm install
+    - run: npm run test
+    - run: npm run check-formatting

.gitignore

@@ -15,6 +15,7 @@ yarn-debug.log*
 yarn-error.log*
 
 package-lock.json
+yarn.lock
 
 #ide's
 .vscode
@@ -23,4 +24,11 @@ package-lock.json
 node_modules
 
 # Extras temp file
-/tools/owl.js
+/tools/owl.js
+
+release-notes.md
+
+.rpt2_cache
+
+# useful in some cases
+/temp

README.md

@@ -1,4 +1,8 @@
-<h1 align="center">🦉 <a href="https://odoo.github.io/owl/">Odoo Web Library</a> 🦉</h1>
+<h1 align="center">🦉 <a href="https://odoo.github.io/owl/">OWL Framework</a> 🦉</h1>
+
+ [![License: LGPL v3](https://img.shields.io/badge/License-LGPL%20v3-blue.svg)](https://www.gnu.org/licenses/lgpl-3.0)
+[![npm version](https://badge.fury.io/js/@odoo%2Fowl.svg)](https://badge.fury.io/js/@odoo%2Fowl)
+[![Downloads](https://img.shields.io/npm/dm/@odoo%2Fowl.svg)](https://www.npmjs.com/package/@odoo/owl)
 
 _Class based components with hooks, reactive state and concurrent mode_
 
@@ -11,24 +15,37 @@ simple and consistent way. Owl's main features are:
 
 - a declarative component system,
 - a reactivity system based on hooks,
-- a store implementation (for state management),
-- a small frontend router
+- concurrent mode by default,
+- a store and a frontend router
 
-Owl components are defined with ES6 classes, they use QWeb templates, an underlying
-virtual dom, integrates beautifully with hooks, and the rendering is asynchronous.
+Owl components are defined with ES6 classes, they use QWeb templates, an
+underlying virtual DOM, integrates beautifully with hooks, and the rendering is
+asynchronous.
 
-**Try it online!** An online playground is available at [https://odoo.github.io/owl/playground](https://odoo.github.io/owl/playground) to let you experiment with the Owl framework. There
-are some code examples to showcase some interesting features.
+**Try it online!** An online playground is available at
+[https://odoo.github.io/owl/playground](https://odoo.github.io/owl/playground)
+to let you experiment with the Owl framework. There are some code examples to
+showcase some interesting features.
 
-Owl is currently mostly stable.  Possible future changes are explained in the
+Owl is currently stable.  Possible future changes are explained in the
 [roadmap](roadmap.md).
 
+## Why Owl?
+
+Why did Odoo decide to make Yet Another Framework?  This is really a question
+that deserves [a long answer](doc/miscellaneous/why_owl.md). But in short, we believe that
+while the current state of the art frameworks are excellent, they are not
+optimized for our use case, and there is still room for something else.
+
+If you are interested in a comparison with React or Vue, you will
+find some more additional information [here](doc/miscellaneous/comparison.md).
+
 ## Example
 
 Here is a short example to illustrate interactive components:
 
 ```javascript
-const { Component, useState } = owl;
+const { Component, useState, mount } = owl;
 const { xml } = owl.tags;
 
 class Counter extends Component {
@@ -50,8 +67,7 @@ class App extends Component {
   static components = { Counter };
 }
 
-const app = new App();
-app.mount(document.body);
+mount(App, { target: document.body });
 ```
 
 Note that the counter component is made reactive with the [`useState` hook](doc/reference/hooks.md#usestate).
@@ -79,10 +95,9 @@ requirements are common and code needs to be maintained by large teams.
 
 Owl is not designed to be fast nor small (even though it is quite good on those
 two topics). It is a no nonsense framework to build applications. There is only
-one way to define components (with classes).
+one way to define components (with classes). There is no black magic. It just
+works.
 
-If you are interested in a comparison with React or Vue, you will
-find some more information [here](doc/comparison.md).
 
 ## Documentation
 
@@ -90,162 +105,26 @@ A complete documentation for Owl can be found here:
 
 - [Main documentation page](doc/readme.md).
 
-The most important sections are:
+Some of the most important pages are:
 
 - [Tutorial: TodoList application](doc/learning/tutorial_todoapp.md)
+- [How to start an Owl project](doc/learning/quick_start.md)
 - [QWeb templating language](doc/reference/qweb_templating_language.md)
 - [Component](doc/reference/component.md)
 - [Hooks](doc/reference/hooks.md)
 
-Found an issue in the documentation? A broken link? Some outdated information?
-Submit a PR!
 
-## Installing/Building
+## Installing Owl
+
+Owl is available on `npm` and can be installed with the following command:
+
+```
+npm install @odoo/owl
+```
 
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-1.0.0-beta2.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.js)
-- [owl-1.0.0-beta2.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.min.js)
-
-Some npm scripts are available:
-
-| Command          | Description                                        |
-| ---------------- | -------------------------------------------------- |
-| `npm install`    | install every dependency required for this project |
-| `npm run build`  | build a bundle of _owl_ in the _/dist/_ folder     |
-| `npm run minify` | minify the prebuilt owl.js file                    |
-| `npm run test`   | run all (owl) tests                                |
-
-## Quick Overview
-
-Owl components in an application are used to define a (dynamic) tree of components.
-
-```
-        Root
-        /   \
-       A     B
-      / \
-     C   D
-```
-
-**State:** each component can manage its own local state. It is a simple ES6
-class, there are no special rules:
-
-```js
-class Counter extends Component {
-  static template = xml`
-    <button t-on-click="increment">
-      Click Me! [<t t-esc="state.value"/>]
-    </button>`;
-
-  state = { value: 0 };
-
-  increment() {
-    this.state.value++;
-    this.render();
-  }
-}
-```
-
-The example above shows a component with a local state. Note that since there
-is nothing magical to the `state` object, we need to manually call the `render`
-function whenever we update it. This can quickly become annoying (and not
-efficient if we do it too much). There is a better way: using the `useState`
-hook, which transforms an object into a reactive version of itself:
-
-```js
-const { useState } = owl.hooks;
-
-class Counter extends Component {
-  static template = xml`
-    <button t-on-click="increment">
-      Click Me! [<t t-esc="state.value"/>]
-    </button>`;
-
-  state = useState({ value: 0 });
-
-  increment() {
-    this.state.value++;
-  }
-}
-```
-
-Note that the `t-on-click` handler can even be replaced by an inline statement:
-
-```xml
-    <button t-on-click="state.value++">
-```
-
-**Props:** sub components often needs some information from their parents. This
-is done by adding the required information to the template. This will then be
-accessible by the sub component in the `props` object. Note that there is an
-important rule here: the information contained in the `props` object is not
-owned by the sub component, and should never be modified.
-
-```js
-class Child extends Component {
-  static template = xml`<div>Hello <t t-esc="props.name"/></div>`;
-}
-
-class Parent extends Component {
-  static template = xml`
-    <div>
-        <Child name="'Owl'" />
-        <Child name="'Framework'" />
-    </div>`;
-  static components = { Child };
-}
-```
-
-**Communication:** there are multiple ways to communicate information between
-components. However, the two most important ways are the following:
-
-- from parent to children: by using `props`,
-- from a children to one of its parent: by triggering events.
-
-The following example illustrate both mechanisms:
-
-```js
-class OrderLine extends Component {
-  static template = xml`
-    <div t-on-click="add">
-        <div><t t-esc="props.line.name"/></div>
-        <div>Quantity: <t t-esc="props.line.quantity"/></div>
-    </div>`;
-
-  add() {
-    this.trigger("add-to-order", { line: props.line });
-  }
-}
-
-class Parent extends Component {
-  static template = xml`
-    <div t-on-add-to-order="addToOrder">
-        <OrderLine
-            t-foreach="orders"
-            t-as="line"
-            line="line" />
-    </div>`;
-  static components = { OrderLine };
-  orders = useState([{ id: 1, name: "Coffee", quantity: 0 }, { id: 2, name: "Tea", quantity: 0 }]);
-
-  addToOrder(event) {
-    const line = event.detail.line;
-    line.quantity++;
-  }
-}
-```
-
-In this example, the `OrderLine` component trigger a `add-to-order` event. This
-will generate a DOM event which will bubble along the DOM tree. It will then be
-intercepted by the parent component, which will then get the line (from the
-`detail` key) and then increment its quantity. See the section on [event handling](doc/reference/component.md#event-handling)
-for more details on how events work.
-
-Note that this example would have also worked if the `OrderLine` component
-directly modifies the `line` object. However, this is not a good practice: this
-only works because the `props` object received by the child component is reactive,
-so the child component is then coupled to the parents implementation.
+- [owl-1.4.9](https://github.com/odoo/owl/releases/tag/v1.4.9)
 
 ## License
 

doc/learning/how_to_debug.md

@@ -0,0 +1,43 @@
+# 🦉 How to debug Owl applications 🦉
+
+Non trivial applications become quickly more difficult to understand. It is then
+useful to have a solid understanding of what is going on. To help with that,
+logging useful information is extremely valuable. There is a [javascript file](../../tools/debug.js) which can be evaluated in an application.
+
+Once it is executed, it will log a lot of information on each component main hooks. The following code is a minified version to make it easier to copy/paste:
+
+```
+function debugOwl(t,e){let n,o="[OWL_DEBUG]";function r(t){let e;try{e=JSON.stringify(t||{})}catch(t){e="<JSON error>"}return e.length>200&&(e=e.slice(0,200)+"..."),e}if(Object.defineProperty(t.Component,"current",{get:()=>n,set(s){n=s;const i=s.constructor.name;if(e.componentBlackList&&e.componentBlackList.test(i))return;if(e.componentWhiteList&&!e.componentWhiteList.test(i))return;let l;Object.defineProperty(n,"__owl__",{get:()=>l,set(n){!function(n,s,i){let l=`${s}<id=${i}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!e.methodBlackList||!e.methodBlackList.includes(t))&&!(e.methodWhiteList&&!e.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${r(n.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${r(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=n.__render.bind(n);n.__render=function(...t){c("rendering template"),d(...t)};const h=n.render.bind(n);n.render=function(...t){const e=n.__owl__;let o="render";return e.isMounted||e.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=n.mount.bind(n);n.mount=function(...t){return c("mount"),p(...t)}}(s,i,(l=n).id)}})}}),e.logScheduler){let e=t.Component.scheduler.start,n=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),e.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),n.call(this)}}if(e.logStore){let e=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...n){return console.log(`${o} store: action '${t}' dispatched. Payload: '${r(n)}'`),e.call(this,t,...n)}}}
+debugOwl(owl, {
+  // componentBlackList: /App/,  // regexp
+  // componentWhiteList: /SomeComponent/, // regexp
+  // methodBlackList: ["mounted"], // list of method names
+  // methodWhiteList: ["willStart"], // list of method names
+  logScheduler: false,  // display/mute scheduler logs
+  logStore: true,     // display/mute store logs
+});
+```
+
+The above code, once pasted somewhere in the main javascript file of an owl
+application, will log information looking like this:
+
+```
+[OWL_DEBUG] TodoApp<id=1> constructor, props={}
+[OWL_DEBUG] TodoApp<id=1> mount
+[OWL_DEBUG] TodoApp<id=1> willStart
+[OWL_DEBUG] TodoApp<id=1> rendering template
+[OWL_DEBUG] TodoItem<id=2> constructor, props={"id":2,"completed":false,"title":"hey"}
+[OWL_DEBUG] TodoItem<id=2> willStart
+[OWL_DEBUG] TodoItem<id=3> constructor, props={"id":4,"completed":false,"title":"aaa"}
+[OWL_DEBUG] TodoItem<id=3> willStart
+[OWL_DEBUG] TodoItem<id=2> rendering template
+[OWL_DEBUG] TodoItem<id=3> rendering template
+[OWL_DEBUG] TodoItem<id=3> mounted
+[OWL_DEBUG] TodoItem<id=2> mounted
+[OWL_DEBUG] TodoApp<id=1> mounted
+```
+
+Each component has an internal `id`, which is very useful when debugging.
+
+Note that it is certainly useful to run this code at some point in an application,
+just to get a feel of what each user action implies, for the framework.

doc/learning/how_to_test.md

@@ -1,4 +1,4 @@
-# 🦉 Testing Owl components 🦉
+# 🦉 How to test Components 🦉
 
 ## Content
 
@@ -11,8 +11,7 @@ It is a good practice to test applications and components to ensure that they
 behave as expected. There are many ways to test a user interface: manual
 testing, integration testing, unit testing, ...
 
-In this section, we will discuss how to write unit tests for components, and
-how to debug them if necessary.
+In this section, we will discuss how to write unit tests for components.
 
 ## Unit Tests
 
@@ -86,8 +85,7 @@ afterEach(() => {
 describe("SomeComponent", () => {
   test("component behaves as expected", async () => {
     const props = {...}; // depends on the component
-    const comp = new SomeComponent(null, props);
-    await comp.mount(fixture);
+    const comp = await mount(SomeComponent, { target: fixture, props });
 
     // do some assertions
     expect(...).toBe(...);

doc/learning/how_to_write_sfc.md

@@ -0,0 +1,52 @@
+# 🦉 How to write Single File Components 🦉
+
+It is very useful to group code by feature instead of by type of file. It makes
+it easier to scale application to larger size.
+
+To do so, Owl has two small helpers that make it easy to define a
+template or a stylesheet inside a javascript (or typescript) file: the
+[`xml`](../reference/tags.md#xml-tag) and [`css`](../reference/tags.md#css-tag)
+helper.
+
+This means that the template, the style and the javascript code can be defined in
+the same file. For example:
+
+```js
+const { Component } = owl;
+const { xml, css } = owl.tags;
+
+// -----------------------------------------------------------------------------
+// TEMPLATE
+// -----------------------------------------------------------------------------
+const TEMPLATE = xml/* xml */ `
+	<div class="main">
+		<Sidebar/>
+		<Content />
+	</div>`;
+
+// -----------------------------------------------------------------------------
+// STYLE
+// -----------------------------------------------------------------------------
+const STYLE = css/* css */ `
+  .main {
+    display: grid;
+    grid-template-columns: 200px auto;
+  }
+`;
+
+// -----------------------------------------------------------------------------
+// CODE
+// -----------------------------------------------------------------------------
+class Main extends Component {
+  static template = TEMPLATE;
+  static style = STYLE;
+  static components = { Sidebar, Content };
+
+  // rest of component...
+}
+```
+
+Note that the above example has an inline xml comment, just after the `xml` call.
+This is useful for some editor plugins, such as the VS Code addon
+`Comment tagged template`, which, if installed, add syntax highlighting to the
+content of the template string.

doc/learning/overview.md

@@ -0,0 +1,133 @@
+# 🦉 Quick Overview 🦉
+
+Owl components in an application are used to define a (dynamic) tree of components.
+
+```
+        Root
+        /   \
+       A     B
+      / \
+     C   D
+```
+
+**State:** each component can manage its own local state. It is a simple ES6
+class, there are no special rules:
+
+```js
+class Counter extends Component {
+  static template = xml`
+    <button t-on-click="increment">
+      Click Me! [<t t-esc="state.value"/>]
+    </button>`;
+
+  state = { value: 0 };
+
+  increment() {
+    this.state.value++;
+    this.render();
+  }
+}
+```
+
+The example above shows a component with a local state. Note that since there
+is nothing magical to the `state` object, we need to manually call the `render`
+function whenever we update it. This can quickly become annoying (and not
+efficient if we do it too much). There is a better way: using the `useState`
+hook, which transforms an object into a reactive version of itself:
+
+```js
+const { useState } = owl.hooks;
+
+class Counter extends Component {
+  static template = xml`
+    <button t-on-click="increment">
+      Click Me! [<t t-esc="state.value"/>]
+    </button>`;
+
+  state = useState({ value: 0 });
+
+  increment() {
+    this.state.value++;
+  }
+}
+```
+
+Note that the `t-on-click` handler can even be replaced by an inline statement:
+
+```xml
+    <button t-on-click="state.value++">
+```
+
+**Props:** sub components often needs some information from their parents. This
+is done by adding the required information to the template. This will then be
+accessible by the sub component in the `props` object. Note that there is an
+important rule here: the information contained in the `props` object is not
+owned by the sub component, and should never be modified.
+
+```js
+class Child extends Component {
+  static template = xml`<div>Hello <t t-esc="props.name"/></div>`;
+}
+
+class Parent extends Component {
+  static template = xml`
+    <div>
+        <Child name="'Owl'" />
+        <Child name="'Framework'" />
+    </div>`;
+  static components = { Child };
+}
+```
+
+**Communication:** there are multiple ways to communicate information between
+components. However, the two most important ways are the following:
+
+- from parent to children: by using `props`,
+- from a children to one of its parent: by triggering events.
+
+The following example illustrate both mechanisms:
+
+```js
+class OrderLine extends Component {
+  static template = xml`
+    <div t-on-click="add">
+        <div><t t-esc="props.line.name"/></div>
+        <div>Quantity: <t t-esc="props.line.quantity"/></div>
+    </div>`;
+
+  add() {
+    this.trigger("add-to-order", { line: this.props.line });
+  }
+}
+
+class Parent extends Component {
+  static template = xml`
+    <div t-on-add-to-order="addToOrder">
+        <OrderLine
+            t-foreach="orders"
+            t-as="line"
+            line="line" />
+    </div>`;
+  static components = { OrderLine };
+  orders = useState([
+    { id: 1, name: "Coffee", quantity: 0 },
+    { id: 2, name: "Tea", quantity: 0 },
+  ]);
+
+  addToOrder(event) {
+    const line = event.detail.line;
+    line.quantity++;
+  }
+}
+```
+
+In this example, the `OrderLine` component trigger a `add-to-order` event. This
+will generate a DOM event which will bubble along the DOM tree. It will then be
+intercepted by the parent component, which will then get the line (from the
+`detail` key) and then increment its quantity. See the page on [event handling](../reference/event_handling.md)
+for more details on how events work.
+
+Note that this example would have also worked if the `OrderLine` component
+directly modifies the `line` object. However, this is not a good practice: this
+only works because the `props` object received by the child component is reactive,
+so the child component is then coupled to the parents implementation.

doc/learning/quick_start.md

@@ -1,107 +1,408 @@
-# 🦉 Quick Start 🦉
+# 🦉 How to start an Owl project 🦉
 
-## Static Server
+## Content
 
-Let us assume that we have a static server running somewhere. Let us start by
-adding an html page with a few extra files:
+- [Overview](#overview)
+- [Simple html file](#simple-html-file)
+- [With a static server](#with-a-static-server)
+- [Standard Javascript project](#standard-javascript-project)
+
+## Overview
+
+Each software project has its specific needs. Many of these needs can be solved
+with some tooling: `webpack`, `gulp`, css preprocessor, bundlers, transpilers, ...
+
+Because of that, it is usually not simple to just start a project. Some
+frameworks provide their own tooling to help with that. But then, you have to
+integrate and learn how these applications work.
+
+Owl is designed to be used with no tooling at all. Because of that, Owl can
+"easily" be integrated in a modern build toolchain. In this section, we will
+discuss a few different setups to start a project. Each of these setups has
+advantages and disadvantages in different situations.
+
+## Simple html file
+
+The simplest possible setup is the following: a simple javascript file with your
+code. To do that, let us create the following file structure:
 
 ```
-my-app/
-    index.html
-    app.css
-    app.js
-    owl-X.Y.Z.js
-    templates.xml
+hello_owl/
+  index.html
+  owl.js
+  app.js
 ```
 
-### HTML and CSS
+The file `owl.js` can be downloaded from the last release published at
+[https://github.com/odoo/owl/releases](https://github.com/odoo/owl/releases). It
+is a single javascript file which export all Owl into the global `owl` object.
 
-In a file `index.html`:
+Now, `index.html` should contain the following:
 
 ```html
 <!DOCTYPE html>
 <html lang="en">
   <head>
-    <meta charset="UTF-8" />
-    <title>My OWL App</title>
-    <link href="app.css" rel="stylesheet" />
-    <script src="owl-X.Y.Z.js"></script>
+    <title>Hello Owl</title>
+    <script src="owl.js"></script>
+    <script src="app.js"></script>
   </head>
-  <body>
-    <div id="main"></div>
-    <script src="app.js" type="module"></script>
-  </body>
+  <body></body>
 </html>
 ```
 
-In `app.css`:
+And `app.js` should look like this:
 
-```css
-button {
-  color: darkred;
-  font-size: 30px;
-  width: 220px;
+```js
+const { Component, mount } = owl;
+const { xml } = owl.tags;
+const { whenReady } = owl.utils;
+
+// Owl Components
+class App extends Component {
+  static template = xml`<div>Hello Owl</div>`;
+}
+
+// Setup code
+function setup() {
+  mount(App, target: { document.body })
+}
+
+whenReady(setup);
+```
+
+Now, simply loading this html file in a browser should display a welcome message.
+This setup is not fancy, but it is extremely simple. There are no tooling at
+all required. It can be slightly optimized by using the minified build of Owl.
+
+## With a static server
+
+The previous setup has a big disadvantage: the application code is located in a
+single file. Obviously, we could split it in several files and add multiple
+`<script>` tags in the html page, but then we need to make sure the script are
+inserted in the proper order, we need to export each file content in global
+variables and we lose autocompletion across files.
+
+There is a low tech solution to this issue: using native javascript modules.
+This however has a requirement: for security reasons, browsers will not accept
+modules on content served through the `file` protocol. This means that we need
+to use a static server.
+
+Let us start a new project with the following file structure:
+
+```
+hello_owl/
+  src/
+    app.js
+    index.html
+    main.js
+    owl.js
+```
+
+As previously, the file `owl.js` can be downloaded from the last release published at
+[https://github.com/odoo/owl/releases](https://github.com/odoo/owl/releases).
+
+Now, `index.html` should contain the following:
+
+```html
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <title>Hello Owl</title>
+    <script src="owl.js"></script>
+    <script src="main.js" type="module"></script>
+  </head>
+  <body></body>
+</html>
+```
+
+Not that the `main.js` script tag has the `type="module"` attribute. This means
+that the browser will parse the script as a module, and load all its dependencies.
+
+Here is the content of `app.js` and `main.js`:
+
+```js
+// app.js ----------------------------------------------------------------------
+const { Component, mount } = owl;
+const { xml } = owl.tags;
+
+export class App extends Component {
+  static template = xml`<div>Hello Owl</div>`;
+}
+
+// main.js ---------------------------------------------------------------------
+import { App } from "./app.js";
+
+function setup() {
+  mount(App, { target: document.body });
+}
+
+owl.utils.whenReady(setup);
+```
+
+The `main.js` file import the `app.js` file. Note that the import statement has
+a `.js` suffix, which is important. Most text editor can understand this syntax
+and will provide autocompletion.
+
+Now, to execute this code, we need to serve the `src` folder statically. A low
+tech way to do that is to use for example the python `SimpleHTTPServer` feature:
+
+```
+$ cd src
+$ python -m SimpleHTTPServer 8022    # now content is available at localhost:8022
+```
+
+Another more "javascripty" way to do it is to create a `npm` application. To do
+that, we can add the following `package.json` file at the root of the project:
+
+```json
+{
+  "name": "hello_owl",
+  "version": "0.1.0",
+  "description": "Starting Owl app",
+  "main": "src/index.html",
+  "scripts": {
+    "serve": "serve src"
+  },
+  "author": "John",
+  "license": "ISC",
+  "devDependencies": {
+    "serve": "^11.3.0"
+  }
 }
 ```
 
-Also, let's not forget to add a release of OWL (`owl-X.Y.Z.js`)
+We can now install the `serve` tool with the command `npm install`, and then,
+start a static server with the simple `npm run serve` command.
 
-### XML
+## Standard Javascript project
 
-In `templates.xml`:
+The previous setup works, and is certainly good for some usecases, including
+quick prototyping. However, it lacks some useful features, such as livereload,
+a test suite, or bundling the code in a single file.
 
-```xml
-<templates>
-   <button t-name="clickcounter" t-on-click="increment">
-      Click Me! [<t t-esc="state.value"/>]
-    </button>
-</templates>
+Each of these features, and many others, can be done in many different ways.
+Since it is really not trivial to configure such a project, we provide here an
+example that can be used as a starting point.
+
+Our standard Owl project has the following file structure:
+
+```
+hello_owl/
+  public/
+    index.html
+  src/
+    components/
+      App.js
+    main.js
+  tests/
+    components/
+      App.test.js
+    helpers.js
+  .gitignore
+  package.json
+  webpack.config.js
 ```
 
-### JS
+This project as a `public` folder, meant to contain all static assets, such as
+images and styles. The `src` folder has the javascript source code, and finally,
+`tests` contains the test suite.
 
-To build an application (or a sub-part of an application), we need two things:
+Here is the content of `index.html`:
 
-- an environment: it is the global context in which we are working. It needs to
-  contain a QWeb instance (preloaded with templates), and anything else that we
-  need. In practice, it could be used to contain some user session information, some
-  configuration keys (for example, isMobile = true/false if we are in mobile mode).
+```html
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <title>Hello Owl</title>
+  </head>
+  <body></body>
+</html>
+```
 
-- a description of the user interface: there should be a root component, which can
-  have sub components
+Note that there are no `<script>` tag here. They will be injected by webpack.
+Now, let's have a look at the javascript files:
 
-Here are a few steps that we may take to get started:
+```js
+// src/components/App.js -------------------------------------------------------
+import { Component, tags, useState } from "@odoo/owl";
 
-- get the templates
-- create a qweb engine, with the templates
-- create an environment
-- create an instance of the root component
-- mount the root component to a DOM element
+const { xml } = tags;
 
-Let us now add the javascript to make it work, in `app.js`:
-
-```javascript
-const useState = owl.hooks.useState;
-
-class ClickCounter extends owl.Component {
-  static template = "clickcounter";
-  state = useState({ value: 0 });
-
-  increment() {
-    this.state.value++;
+export class App extends Component {
+  static template = xml`<div t-on-click="update">Hello <t t-esc="state.text"/></div>`;
+  state = useState({ text: "Owl" });
+  update() {
+    this.state.text = this.state.text === "Owl" ? "World" : "Owl";
   }
 }
 
-//------------------------------------------------------------------------------
-// Application initialization
-//------------------------------------------------------------------------------
-async function start() {
-  const templates = await owl.utils.loadFile("templates.xml");
-  ClickCounter.env = { qweb: new owl.QWeb({ templates }) };
-  const counter = new ClickCounter();
-  const target = document.getElementById("main");
-  await counter.mount(target);
+// src/main.js -----------------------------------------------------------------
+import { utils, mount } from "@odoo/owl";
+import { App } from "./components/App";
+
+function setup() {
+  mount(App, { target: document.body });
 }
 
-start();
+utils.whenReady(setup);
+
+// tests/components/App.test.js ------------------------------------------------
+import { App } from "../../src/components/App";
+import { makeTestFixture, nextTick, click } from "../helpers";
+import { mount } from "@odoo/owl";
+
+let fixture;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("App", () => {
+  test("Works as expected...", async () => {
+    await mount(App, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div>Hello Owl</div>");
+
+    click(fixture, "div");
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div>Hello World</div>");
+  });
+});
+
+// tests/helpers.js ------------------------------------------------------------
+import { Component } from "@odoo/owl";
+import "regenerator-runtime/runtime";
+
+export async function nextTick() {
+  return new Promise(function (resolve) {
+    setTimeout(() => Component.scheduler.requestAnimationFrame(() => resolve()));
+  });
+}
+
+export function makeTestFixture() {
+  let fixture = document.createElement("div");
+  document.body.appendChild(fixture);
+  return fixture;
+}
+
+export function click(elem, selector) {
+  elem.querySelector(selector).dispatchEvent(new Event("click"));
+}
+```
+
+Finally, here is the configuration files `.gitignore`, `package.json` and
+`webpack.config.js`:
+
+```
+node_modules/
+package-lock.json
+dist/
+```
+
+```json
+{
+  "name": "hello_owl",
+  "version": "0.1.0",
+  "description": "Demo app",
+  "main": "src/index.html",
+  "scripts": {
+    "test": "jest",
+    "build": "webpack --mode production",
+    "dev": "webpack-dev-server --mode development"
+  },
+  "author": "Someone",
+  "license": "ISC",
+  "devDependencies": {
+    "@babel/core": "^7.8.4",
+    "@babel/plugin-proposal-class-properties": "^7.8.3",
+    "babel-jest": "^25.1.0",
+    "babel-loader": "^8.0.6",
+    "babel-plugin-transform-es2015-modules-commonjs": "^6.26.2",
+    "html-webpack-plugin": "^3.2.0",
+    "jest": "^25.1.0",
+    "regenerator-runtime": "^0.13.3",
+    "serve": "^11.3.0",
+    "webpack": "^4.41.5",
+    "webpack-cli": "^3.3.10",
+    "webpack-dev-server": "^3.10.2"
+  },
+  "dependencies": {
+    "@odoo/owl": "^1.0.4"
+  },
+  "babel": {
+    "plugins": ["@babel/plugin-proposal-class-properties"],
+    "env": {
+      "test": {
+        "plugins": ["transform-es2015-modules-commonjs"]
+      }
+    }
+  },
+  "jest": {
+    "verbose": false,
+    "testRegex": "(/tests/.*(test|spec))\\.js?$",
+    "moduleFileExtensions": ["js"],
+    "transform": {
+      "^.+\\.[t|j]sx?$": "babel-jest"
+    }
+  }
+}
+```
+
+```js
+const path = require("path");
+const HtmlWebpackPlugin = require("html-webpack-plugin");
+
+const host = process.env.HOST || "localhost";
+
+module.exports = function (env, argv) {
+  const mode = argv.mode || "development";
+  return {
+    mode: mode,
+    entry: "./src/main.js",
+    output: {
+      filename: "main.js",
+      path: path.resolve(__dirname, "dist"),
+    },
+    module: {
+      rules: [
+        {
+          test: /\.jsx?$/,
+          loader: "babel-loader",
+          exclude: /node_modules/,
+        },
+      ],
+    },
+    resolve: {
+      extensions: [".js", ".jsx"],
+    },
+    devServer: {
+      contentBase: path.resolve(__dirname, "public/index.html"),
+      compress: true,
+      hot: true,
+      host,
+      port: 3000,
+      publicPath: "/",
+    },
+    plugins: [
+      new HtmlWebpackPlugin({
+        inject: true,
+        template: path.resolve(__dirname, "public/index.html"),
+      }),
+    ],
+  };
+};
+```
+
+With this setup, we can now use the following script commands:
+
+```
+npm run build # build the full application in prod mode in dist/
+
+npm run dev # start a dev server with livereload
+
+npm run test # run the jest test suite
 ```

doc/learning/tutorial_todoapp.md

@@ -37,7 +37,7 @@ todoapp/
     index.html
     app.css
     app.js
-    owl.min.js
+    owl.js
 ```
 
 The entry point for this application is the file `index.html`, which should have
@@ -62,7 +62,7 @@ our application. `app.js` is where we will write all our code. For now, let's
 just put the following code:
 
 ```js
-(function() {
+(function () {
   console.log("hello owl", owl.__info__.version);
 })();
 ```
@@ -70,7 +70,9 @@ just put the following code:
 Note that we put everything inside an immediately executed function to avoid leaking
 anything to the global scope.
 
-Finally, `owl.js` should be the last version downloaded from the Owl repository (you can use `owl.min.js` if you prefer).
+Finally, `owl.js` should be the last version downloaded from the Owl repository (you can use `owl.min.js` if you prefer). Be aware that you should download the `owl.iife.js` or `owl.iife.min.js`, because these files
+are built to run directly on the browser (other files such as `owl.cjs.js` are
+built to be bundled by other tools).
 
 Now, the project should be ready. Loading the `index.html` file into a browser
 should show an empty page, with the title `Owl Todo App`, and it should log a
@@ -83,7 +85,7 @@ a single root component. Let us start by defining an `App` component. Replace th
 content of the function in `app.js` by the following code:
 
 ```js
-const { Component } = owl;
+const { Component, mount } = owl;
 const { xml } = owl.tags;
 const { whenReady } = owl.utils;
 
@@ -94,8 +96,7 @@ class App extends Component {
 
 // Setup code
 function setup() {
-  const app = new App();
-  app.mount(document.body);
+  mount(App, { target: document.body });
 }
 
 whenReady(setup);
@@ -170,13 +171,13 @@ class App extends Component {
     {
       id: 1,
       title: "buy milk",
-      isCompleted: true
+      isCompleted: true,
     },
     {
       id: 2,
       title: "clean house",
-      isCompleted: false
-    }
+      isCompleted: false,
+    },
   ];
 }
 ```
@@ -279,8 +280,7 @@ class App extends Component {
 // -------------------------------------------------------------------------
 function setup() {
     owl.config.mode = "dev";
-    const app = new App();
-    app.mount(document.body);
+    mount(App, { target: document.body });
 }
 
 whenReady(setup);
@@ -446,7 +446,7 @@ Now, this is an interesting situation: the task is displayed by the `Task`
 component, but it is not the owner of its state, so it cannot modify it. Instead,
 we want to communicate the request to toggle a task to the `App` component.
 Since `App` is a parent of `Task`, we can
-[trigger](../reference/component.md#event-handling) an event in `Task` and listen
+[trigger](../reference/event_handling.md) an event in `Task` and listen
 for it in `App`.
 
 In `Task`, change the `input` to:
@@ -547,7 +547,7 @@ application), since it involves extracting all task related code out of the
 components. Here is the new content of the `app.js` file:
 
 ```js
-const { Component, Store } = owl;
+const { Component, Store, mount } = owl;
 const { xml } = owl.tags;
 const { whenReady } = owl.utils;
 const { useRef, useDispatch, useStore } = owl.hooks;
@@ -562,23 +562,23 @@ const actions = {
       const task = {
         id: state.nextId++,
         title: title,
-        isCompleted: false
+        isCompleted: false,
       };
       state.tasks.push(task);
     }
   },
   toggleTask({ state }, id) {
-    const task = state.tasks.find(t => t.id === id);
+    const task = state.tasks.find((t) => t.id === id);
     task.isCompleted = !task.isCompleted;
   },
   deleteTask({ state }, id) {
-    const index = state.tasks.findIndex(t => t.id === id);
+    const index = state.tasks.findIndex((t) => t.id === id);
     state.tasks.splice(index, 1);
-  }
+  },
 };
 const initialState = {
   nextId: 1,
-  tasks: []
+  tasks: [],
 };
 
 // -------------------------------------------------------------------------
@@ -616,7 +616,7 @@ class App extends Component {
   static components = { Task };
 
   inputRef = useRef("add-input");
-  tasks = useStore(state => state.tasks);
+  tasks = useStore((state) => state.tasks);
   dispatch = useDispatch();
 
   mounted() {
@@ -639,8 +639,7 @@ function setup() {
   owl.config.mode = "dev";
   const store = new Store({ actions, state: initialState });
   App.env.store = store;
-  const app = new App();
-  app.mount(document.body);
+  mount(App, { target: document.body });
 }
 
 whenReady(setup);
@@ -666,9 +665,8 @@ function makeStore() {
 
 function setup() {
   owl.config.mode = "dev";
-  App.env.store = makeStore();
-  const app = new App();
-  app.mount(document.body);
+  const env = { store: makeStore() };
+  mount(App, { target: document.body, env });
 }
 ```
 
@@ -811,8 +809,8 @@ For reference, here is the final code:
 ```
 
 ```js
-(function() {
-  const { Component, Store } = owl;
+(function () {
+  const { Component, Store, mount } = owl;
   const { xml } = owl.tags;
   const { whenReady } = owl.utils;
   const { useRef, useDispatch, useState, useStore } = owl.hooks;
@@ -827,24 +825,24 @@ For reference, here is the final code:
         const task = {
           id: state.nextId++,
           title: title,
-          isCompleted: false
+          isCompleted: false,
         };
         state.tasks.push(task);
       }
     },
     toggleTask({ state }, id) {
-      const task = state.tasks.find(t => t.id === id);
+      const task = state.tasks.find((t) => t.id === id);
       task.isCompleted = !task.isCompleted;
     },
     deleteTask({ state }, id) {
-      const index = state.tasks.findIndex(t => t.id === id);
+      const index = state.tasks.findIndex((t) => t.id === id);
       state.tasks.splice(index, 1);
-    }
+    },
   };
 
   const initialState = {
     nextId: 1,
-    tasks: []
+    tasks: [],
   };
 
   // -------------------------------------------------------------------------
@@ -897,7 +895,7 @@ For reference, here is the final code:
     static components = { Task };
 
     inputRef = useRef("add-input");
-    tasks = useStore(state => state.tasks);
+    tasks = useStore((state) => state.tasks);
     filter = useState({ value: "all" });
     dispatch = useDispatch();
 
@@ -916,9 +914,9 @@ For reference, here is the final code:
     get displayedTasks() {
       switch (this.filter.value) {
         case "active":
-          return this.tasks.filter(t => !t.isCompleted);
+          return this.tasks.filter((t) => !t.isCompleted);
         case "completed":
-          return this.tasks.filter(t => t.isCompleted);
+          return this.tasks.filter((t) => t.isCompleted);
         case "all":
           return this.tasks;
       }
@@ -943,9 +941,8 @@ For reference, here is the final code:
 
   function setup() {
     owl.config.mode = "dev";
-    App.env.store = makeStore();
-    const app = new App();
-    app.mount(document.body);
+    const env = { store: makeStore() };
+    mount(App, { target: document.body, env });
   }
 
   whenReady(setup);

doc/miscellaneous/comparison.md

@@ -4,7 +4,7 @@ OWL, React and Vue have the same main feature: they allow developers to build
 declarative user interfaces. To do that, all these frameworks uses a virtual dom. However, there are still obviously many differences.
 
 In this page, we try to highlight some of these differences. Obviously, a lot of
-effort was done to be fair. However, if you disagree with some of the points
+effort was put to be fair. However, if you disagree with some of the points
 discussed, feel free to open an issue/submit a PR to correct this text.
 
 ## Content
@@ -47,7 +47,7 @@ components are fast enough for all our usecases, and making it as simple as
 possible for developers is more valuable (for us).
 
 Also, functions or class based components are more than just syntax. Functions
-comes with a mindset of composition and class are about inheritance. Clearly,
+come with a mindset of composition and class are about inheritance. Clearly,
 both of these are important mechanisms for reusing code. Also, one does not
 exclude the other.
 
@@ -79,7 +79,7 @@ additional tools, we made a lot of effort to make the most of the web platform.
 
 For example, Owl uses the standard `xml` parser that comes with every browser.
 Because of that, Owl did not have to write its own template parser. Another
-example is the [`xml`](reference/tags.md#xml-tag) tag helper function, which makes use of
+example is the [`xml`](../reference/tags.md#xml-tag) tag helper function, which makes use of
 native template literals to allow in a natural way to write `xml` templates
 directly in the javascript code. This can be easily integrated with editor
 plugins to have autocompletion inside the template.
@@ -127,7 +127,7 @@ structured than a template language. Note that the tooling is quite impressive:
 there is a syntax highlighter for jsx here on github!
 
 By comparison, here is the equivalent Owl component, written with the
-[`xml`](reference/tags.md#xml-tag) tag helper:
+[`xml`](../reference/tags.md#xml-tag) tag helper:
 
 ```js
 class Clock extends Component {
@@ -251,17 +251,17 @@ keeps track of who get data, and retrigger a render when it was changed.
 Owl store is a little bit like a mix of redux and vuex: it has actions (but not
 mutations), and like VueX, it keeps track of the state changes. However, it does
 not notify a component when the state changes. Instead, components need to connect
-to the store like in redux, with the `useStore` hook (see the [store documentation](reference/store.md#connecting-a-component)).
+to the store like in redux, with the `useStore` hook (see the [store documentation](../reference/store.md#connecting-a-component)).
 
 ```javascript
 const actions = {
   increment({ state }, val) {
     state.counter.value += val;
-  }
+  },
 };
 
 const state = {
-  counter: { value: 0 }
+  counter: { value: 0 },
 };
 const store = new owl.Store({ state, actions });
 
@@ -270,7 +270,7 @@ class Counter extends Component {
       <button t-name="Counter" t-on-click="dispatch('increment')">
         Click Me! [<t t-esc="counter.value"/>]
       </button>`;
-  counter = useStore(state => state.counter);
+  counter = useStore((state) => state.counter);
   dispatch = useDispatch();
 }
 
@@ -315,7 +315,7 @@ This work is based on the new ideas introduced by React hooks.
 
 From the way React and Vue introduce their hooks, it may look like hooks are not
 compatible with class components. However, this is not the case, as shown by
-Owl [hooks](reference/hooks.md). They are inspired by both React and Vue. For example,
+Owl [hooks](../reference/hooks.md). They are inspired by both React and Vue. For example,
 the `useState` hook is named after React, but its API is closer to the `reactive`
 Vue hook.
 

doc/miscellaneous/why_owl.md

@@ -0,0 +1,180 @@
+# 🦉 Why Owl ? 🦉
+
+The common wisdom is that one should not reinvent the wheel, because that would
+waste effort and resources. It is certainly true in many cases. A javascript
+framework is a considerable investment, so it is quite logical to ask the question:
+why did Odoo decide to make OWL instead of using a standard/well known framework,
+such as React or Vue?
+
+As you might expect, the answer to that question is not simple. But most of the
+reasons discussed in this page are a consequence from a single fact: Odoo is
+extremely modular.
+
+This means, for example, that the core parts of Odoo are not aware, before runtime,
+of what files will be loaded/executed, or what will be the state of the UI. Because
+of that, Odoo cannot rely on a standard build toolchain. Also, this implies that
+the core parts of Odoo need to be extremely generic. In other words, Odoo is not
+really an application with a user interface. It is an application which generates
+a dynamic user interface. And most frameworks are not up to the task.
+
+Betting on Owl was not an easy choice to make, because there certainly are a lot
+of conflicting needs that we want to carefully balance. Choosing anything other
+than a well known framework is bound to be controversial. This page will explain
+some of the reason why we still believe that building Owl is a worthwile
+endeavour.
+
+## Strategy
+
+It is true that we want to keep control of our technology, in the sense that we
+do not want to depend on Facebook or Google, or any other large (or small)
+company. If they decide to change their license, or to go in a direction that
+will not work for us, this may be a problem. This is even more true because
+Odoo is not a conventional javascript application, and our needs are probably
+quite different as most other applications.
+
+## Class components
+
+It is clear that the biggest frameworks are moving away from class components.
+There is an implicit assumption that class components are terrible, and that
+functional programming is the way to go. React even goes as far as to say that
+classes are confusing for developers.
+
+While there is some truth to that, and to the fact that composition is certainly
+a good mechanism for code reuse, we believe that classes and inheritance are
+important tools.
+
+Sharing code between generic components with inheritance is the way Odoo built
+its web client. And it is clear that inheritance is not the root of all evils.
+It is often a perfectly simple and appropriate solution. What matter most is
+the architectural decisions.
+
+Also, Odoo has another specific use out of class components: each method of a
+class provides an extension point for addons. This may not be a clean architecture
+pattern, but it is a pragmatic decision that served Odoo well: classes are
+sometimes monkey-patched to add behaviour from the outside. A little bit like
+mixins, but from the outside.
+
+Using React or Vue would make it significantly harder to monkey patch components,
+because a lot of the state is hidden in their internals.
+
+## Tooling
+
+React or Vue have a huge community, and a lot of effort have been made into their
+tooling. This is wonderful, but at the same time, a pretty big issue for Odoo:
+since the assets are totally dynamic (and could change whenever the user installs
+or removes an addon), we need to have all that kind of tooling on the production
+servers. This is certainly not ideal.
+
+Also, this makes it very complicated to setup Vue or React tools: Odoo code is
+not a simple file that import other files. It changes all the time, assets
+are bundled differently in different contexts. This is the reason why Odoo has
+its own module system, which are resolved at runtime, by the browser. The
+dynamic nature of Odoo means that we often need to delay work as late as possible
+(in other word, we want a JIT user interface!)
+
+Our ideal framework has minimal (mandatory) tooling, which makes it easier to
+deploy. Using React without JSX, or Vue without vue file is not very appealing.
+
+At the same time, Owl is designed to solve this issue: it compiles templates
+by the browser, it doesn't need much code for that, since we use the XML parser
+built into each browser. Owl works with or without any additional tooling. It
+can use template strings to write single file components, and is easy to integrate
+in any html page, with a simple `<script>` tag.
+
+## Template based
+
+Odoo stores templates as XML documents in a database. This is very powerful, since
+this allow the use of xpaths to customize other templates. This is a very
+important feature of odoo, and one of the key to Odoo modularity.
+
+Because of that, we still expect to write our templates in an XML document.
+Weirdly enough, no major framework uses XML to store templates, even though it
+is extremely convenient.
+
+So, using React or Vue means that we need to make a template compiler. For React,
+that would be a compiler that would take a QWeb template, and convert it to a
+React render function. For Vue, it would convert it to a Vue template. Then
+we need to bundle the vue template compiler as well.
+
+Not only this would be complex (compiling a templating language into another is
+not an easy task), but it would negatively impact the developer experience as
+well. Writing Vue or React components in a QWeb template would certainly be
+awkward, and very confusing.
+
+## Developer Experience
+
+This brings us to the following point: developer experience. We see this choice
+as an investment for the future, and we want to make onboarding developers as
+easy as possible.
+
+While many javascript professionals clearly think that react/vue is not difficult
+(which is true to some extent), it is alsy true that many non js specialists are
+overwhelmed with the frontend world: functional components, hooks, and many other
+fancy words. Also, what is available in the compilation context may be difficult,
+there is a lot of black magic going on in pretty much every framework. Vue
+somehow join various namespaces into one, under the hood, and add various internal
+keys. Svelte transform the code. React require that state transformations are
+deep, and not shallow.
+
+Owl is trying very hard to have a simple and familiar API. It uses classes. Its
+reactivity system is explicit, not implicit. The scoping rules are obvious. In
+case of doubt, we err on the side of not implementing a feature.
+
+It is certainly different from React or Vue, but at the same time, kind of
+familiar for experienced developers.
+
+## JIT compilation
+
+There is also a clear trend in the frontend world to compile code
+as much as possible ahead of time. Most frameworks will compile templates ahead
+of time. And now Svelte is trying to compile the JS code away, so it can remove
+itself from the bundle.
+
+This is certainly reasonable for many usecases. However, this is not what Odoo
+needs: Odoo will fetch templates from the database and need to compile them only
+at the last possible moment, so we can apply all necessary xpaths.
+
+Even more: Odoo needs to be able to generate (and compile) templates at runtime.
+Currently, Odoo form views interpret an xml description. But the form view code
+then needs to do a lot of complicated operations. With Owl, we will be able to
+transform a view description into a QWeb template, then compile that and use it
+immediately.
+
+## Reactivity
+
+There are other design choices that we feel are not optimal in other frameworks.
+For example, the reactivity system. We like the way Vue did it, but it has a
+flaw: it is not really optional. There is actually a way to opt out of the reactivity
+system by freezing the state, but then, it is freezed.
+
+And there certainly are situations where we need a state, which is not read-only,
+and not observed. For example, imagine a spreadsheet component. It may have a
+very large internal state, and it knows exactly when it needs to be rendered
+(basically, whenever the user performs some action). Then, observing its state
+is a net performance loss, both for the CPU and the memory.
+
+## Concurrency
+
+Many applications are happy to simply display a spinner whenever a new asynchronous
+action is performed, but Odoo wants a different user experience: most asynchronous
+state changes are not displayed until ready. This is sometimes called a concurrent
+mode: the UI is rendered in memory, and displayed only when it is ready (and
+only if it has not been cancelled by subsequent user actions).
+
+React has now an experimental concurrent mode, but it was not ready when Owl
+started. Vue has not really an equivalent API (suspense is not what we need).
+
+Also, React concurrent mode is complex to use. Concurrency was one of the rare
+strong point of the former Odoo js framework (widgets), and we feel that Owl has
+now a very strong concurrent mode, which is simple and powerful at the same time.
+
+## Conclusion
+
+This lengthy discussion showed that there are many small and not so small reasons
+that current standard frameworks are not tailored to our needs. It is perfectly
+fine, because they each chose a different set of tradeoffs.
+
+However, we feel that there is still room in the framework world for something
+that is different. For a framework that makes choices compatible with Odoo.
+
+And that is why we built Owl 🦉.

doc/readme.md

@@ -1,15 +1,34 @@
 # 🦉 OWL Documentation 🦉
 
+## Learning Owl
+
+Are you new to Owl? This is the place to start!
+
+- [Tutorial: create a TodoList application](learning/tutorial_todoapp.md)
+- [Quick Overview](learning/overview.md)
+- [How to start an Owl project](learning/quick_start.md)
+- [How to test Components](learning/how_to_test.md)
+- [How to write Single File Components](learning/how_to_write_sfc.md)
+- [How to write debug Owl applications](learning/how_to_debug.md)
+
 ## Reference
 
+You will find here a complete reference of every feature, class or object
+provided by Owl.
+
 - [Animations](reference/animations.md)
+- [Browser](reference/browser.md)
 - [Component](reference/component.md)
+- [Content](reference/content.md)
 - [Concurrency Model](reference/concurrency_model.md)
 - [Configuration](reference/config.md)
 - [Context](reference/context.md)
 - [Environment](reference/environment.md)
 - [Event Bus](reference/event_bus.md)
+- [Event Handling](reference/event_handling.md)
+- [Error Handling](reference/error_handling.md)
 - [Hooks](reference/hooks.md)
+- [Mounting a component](reference/mounting.md)
 - [Miscellaneous Components](reference/misc.md)
 - [Observer](reference/observer.md)
 - [Props](reference/props.md)
@@ -18,60 +37,21 @@
 - [QWeb Engine](reference/qweb_engine.md)
 - [Router](reference/router.md)
 - [Store](reference/store.md)
+- [Slots](reference/slots.md)
 - [Tags](reference/tags.md)
 - [Utils](reference/utils.md)
 
-## Learning Resources
+## Other Topics
 
-- [Quick Start: create an (almost) empty Owl application](learning/quick_start.md)
-- [Tutorial: create a TodoList application](learning/tutorial_todoapp.md)
-- [Testing Owl components](learning/testing_components.md)
+This section provides miscellaneous document that explains some topics
+which cannot be considered either a tutorial, or reference documentation.
 
-## Miscellaneous
+- [Owl architecture: the Virtual DOM](miscellaneous/vdom.md)
+- [Owl architecture: the rendering pipeline](miscellaneous/rendering.md)
+- [Comparison with React/Vue](miscellaneous/comparison.md)
+- [Why did Odoo built Owl?](miscellaneous/why_owl.md)
 
-- [Comparison with React/Vue](comparison.md)
-- [Tooling](tooling.md)
-- [Templates to start Owl applications (external link)](https://github.com/ged-odoo/owl-templates)
+---
 
-## Architecture
-
-This section explains in more detail the inner workings of Owl. It is targeted
-for developers working on Owl itself.
-
-- [Virtual DOM](architecture/vdom.md)
-- [Rendering](architecture/rendering.md)
-
-## Owl Content
-
-Here is a complete visual representation of everything exported by the `owl`
-global object (so, for example, `Component` is available at `owl.Component`,
-and `EventBus` is exported as `owl.core.EventBus`):
-
-```
-Component                               misc
-Context                                     AsyncRoot
-QWeb                                        Portal
-Store                                   router
-useState                                    Link
-config                                      RouteComponent
-    mode                                    Router
-core                                    tags
-    EventBus                                xml
-    Observer                            utils
-hooks                                       debounce
-    onWillStart                             escape
-    onMounted                               loadJS
-    onWillUpdateProps                       loadFile
-    onWillPatch                             shallowEqual
-    onPatched                               whenReady
-    onWillUnmount
-    useContext
-    useState
-    useRef
-    useSubEnv
-    useStore
-    useDispatch
-    useGetters
-```
-
-Note that for convenience, the `useState` hook is also exported at the root of the `owl` object.
+Found an issue in the documentation? A broken link? Some outdated information?
+Please open an issue or submit a PR!

doc/reference/animations.md

@@ -52,21 +52,20 @@ sequence of events will happen:
 At node insertion:
 
 - the css classes `name-enter` and `name-enter-active` will be added directly
-  when the node is inserted into the DOM,
+  when the node is inserted into the DOM.
 - on the next animation frame: the css class `name-enter` will be removed and the
   class `name-enter-to` will be added (so they can be used to trigger css
-  transition effects),
-- the css class `name-enter-active` will be removed whenever a css transition
-  ends.
+  transition effects).
+- at the end of the transition, `name-enter-to` and `name-enter-active` will be removed.
 
 At node destruction:
 
 - the css classes `name-leave` and `name-leave-active` will be added before the
-  node is removed to the DOM,
-- the css class `name-leave` will be removed on the next animation frame (so it
-  can be used to trigger css transition effects),
-- the css class `name-leave-active` will be removed whenever a css transition
-  ends. Only then will the element be removed from the DOM.
+  node is removed to the DOM.
+- on the next animation frame: the css class `name-leave` will be removed and the
+  class `name-leave-to` will be added (so they can be used to trigger css
+  transition effects).
+- at the end of the transition, `name-leave-to` and `name-leave-active` will be removed.
 
 For example, a simple fade in/out effect can be done with this:
 
@@ -93,3 +92,36 @@ Notes:
 
 Owl does not support more than one transition on a single node, so the
 `t-transition` expression must be a single value (i.e. no space allowed).
+
+## SCSS Mixins
+
+If you use SCSS, you can use mixins to make generic animations. Here is an exemple with a fade in / fade out animation:
+
+```scss
+@mixin animation-fade($time, $name) {
+  .#{$name}_fade-enter-active,
+  .#{$name}_fade-active {
+    transition: all $time;
+  }
+
+  .#{$name}_fade-enter {
+    opacity: 0;
+  }
+
+  .#{$name}_fade-leave-to {
+    opacity: 0;
+  }
+}
+```
+
+Usage:
+
+```scss
+@include animation-fade(0.5s, "o_notification");
+```
+
+You can now have in your template:
+
+```xml
+<SomeTag  t-transition="o_notification_fade"/>
+```

doc/reference/browser.md

@@ -0,0 +1,33 @@
+# 🦉 Browser 🦉
+
+## Content
+
+- [Overview](#overview)
+- [Browser Content](#browser-content)
+
+## Overview
+
+The browser object contains some browser native APIs, such as `setTimeout`, that
+are used by Owl and its utility functions. They are exposed with the intent of
+making them mockable if necessary.
+
+```js
+owl.browser.setTimeout === window.setTimeout; // return true
+```
+
+For now, this object contains some functions that are not used by Owl. They
+will eventually be removed in Owl 2.0.
+
+## Browser Content
+
+More specifically, the `browser` object contains the following methods and objects:
+
+- `setTimeout`
+- `clearTimeout`
+- `setInterval`
+- `clearInterval`
+- `requestAnimationFrame`
+- `random`
+- `Date`
+- `fetch`
+- `localStorage`

doc/reference/component.md

@@ -10,16 +10,22 @@
   - [Static Properties](#static-properties)
   - [Methods](#methods)
   - [Lifecycle](#lifecycle)
+    - [`constructor(parent, props)`](#constructorparent-props)
+    - [`setup()`](#setup)
+    - [`willStart()`](#willstart)
+    - [`mounted()`](#mounted)
+    - [`willUpdateProps(nextProps)`](#willupdatepropsnextprops)
+    - [`willPatch()`](#willpatch)
+    - [`patched(snapshot)`](#patchedsnapshot)
+    - [`willUnmount()`](#willunmount)
+    - [`catchError(error)`](#catcherrorerror)
   - [Root Component](#root-component)
   - [Composition](#composition)
-  - [Event Handling](#event-handling)
   - [Form Input Bindings](#form-input-bindings)
   - [References](#references)
-  - [Slots](#slots)
   - [Dynamic sub components](#dynamic-sub-components)
-  - [Error Handling](#error-handling)
   - [Functional Components](#functional-components)
-  - [SVG components](#svg-components)
+  - [SVG Components](#svg-components)
 
 ## Overview
 
@@ -207,7 +213,7 @@ to be called in the constructor.
   class Counter extends owl.Component {
     static props = {
       initialValue: Number,
-      optional: true
+      optional: true,
     };
   }
   ```
@@ -220,11 +226,15 @@ to be called in the constructor.
   ```js
   class Counter extends owl.Component {
     static defaultProps = {
-      initialValue: 0
+      initialValue: 0,
     };
   }
   ```
 
+- **`style`** (string, optional): it should be the return value of the [`css` tag](tags.md#css-tag),
+  which is used to inject stylesheet whenever the component is visible on the
+  screen.
+
 There is another static property defined on the `Component` class: `current`.
 This property is set to the currently being defined component (in the constructor).
 This is the way [hooks](hooks.md) are able to get a reference to the target
@@ -269,6 +279,10 @@ We explain here all the public methods of the `Component` class.
   // app is now visible
   ```
 
+  Note that the normal way of mounting an application is by using the `mount`
+  method on a component class, not by creating the instance by hand. See the
+  documentation on [mounting applications](mounting.md).
+
 * **`unmount()`**: in case a component needs to be detached/removed from the DOM, this
   method can be used. Most applications should not call `unmount`, this is more
   useful to the underlying component system.
@@ -284,8 +298,13 @@ We explain here all the public methods of the `Component` class.
   are updated. It returns a boolean, which indicates if the component should
   ignore a props update. If it returns false, then `willUpdateProps` will not
   be called, and no rendering will occur. Its default implementation is to
-  always return true. This is an optimization, similar to React's `shouldComponentUpdate`. Most of the time, this should not be used, but it
-  can be useful if we are handling large number of components.
+  always return true. Note that this is an optimization, similar to React's `shouldComponentUpdate`. Most of the time, this should not be used, but it
+  can be useful if we are handling large number of components. Since this is an
+  optimization, Owl has the freedom to ignore the result of `shouldUpdate` in
+  some cases (for example, if a component is remounted, or if we want to force
+  a full rerender of the UI). However, if `shouldUpdate` returns true, then Owl
+  provides the guarantee that the component will be rendered at some point in
+  the future (except if the component is destroyed or if some part of the UI crashes).
 
 * **`destroy()`**. As its name suggests, this method will remove the component,
   and perform all necessary cleanup, such as unmounting the component, its children,
@@ -304,16 +323,16 @@ A solid and robust component system needs useful hooks/methods to help
 developers write components. Here is a complete description of the lifecycle of
 a owl component:
 
-| Method                                           | Description                                                  |
-| ------------------------------------------------ | ------------------------------------------------------------ |
-| **[constructor](#constructorparent-props)**      | constructor                                                  |
-| **[willStart](#willstart)**                      | async, before first rendering                                |
-| **[mounted](#mounted)**                          | just after component is rendered and added to the DOM        |
-| **[willUpdateProps](#willupdatepropsnextprops)** | async, before props update                                   |
-| **[willPatch](#willpatch)**                      | just before the DOM is patched                               |
-| **[patched](#patchedsnapshot)**                  | just after the DOM is patched                                |
-| **[willUnmount](#willunmount)**                  | just before removing component from DOM                      |
-| **[catchError](#catcherrorerror)**               | catch errors (see [error handling section](#error-handling)) |
+| Method                                           | Description                                                 |
+| ------------------------------------------------ | ----------------------------------------------------------- |
+| **[setup](#setup)**                              | setup                                                       |
+| **[willStart](#willstart)**                      | async, before first rendering                               |
+| **[mounted](#mounted)**                          | just after component is rendered and added to the DOM       |
+| **[willUpdateProps](#willupdatepropsnextprops)** | async, before props update                                  |
+| **[willPatch](#willpatch)**                      | just before the DOM is patched                              |
+| **[patched](#patchedsnapshot)**                  | just after the DOM is patched                               |
+| **[willUnmount](#willunmount)**                  | just before removing component from DOM                     |
+| **[catchError](#catcherrorerror)**               | catch errors (see [error handling page](error_handling.md)) |
 
 Notes:
 
@@ -351,6 +370,23 @@ class ClickCounter extends owl.Component {
 }
 ```
 
+Hook functions can be called in the constructor.
+
+#### `setup()`
+
+_setup_ is run just after the component is constructed. It is a lifecycle method,
+very similar to the _constructor_, except that it does not receive any argument.
+
+It is a valid method to call hook functions. Note that one of the main reason to
+have the `setup` hook in the component lifecycle is to make it possible to
+monkey patch it. It is a common need in the Odoo ecosystem.
+
+```javascript
+setup() {
+  useSetupAutofocus();
+}
+```
+
 #### `willStart()`
 
 willStart is an asynchronous hook that can be implemented to
@@ -421,7 +457,7 @@ likely via a change in its state/props or environment).
 
 This method is not called on the initial render. It is useful to interact
 with the DOM (for example, through an external library) whenever the
-component was patched. Note that this hook will not be called if the compoent is
+component was patched. Note that this hook will not be called if the component is
 not in the DOM.
 
 Updating the component state in this hook is possible, but not encouraged.
@@ -448,8 +484,8 @@ This is the opposite method of `mounted`.
 #### `catchError(error)`
 
 The `catchError` method is useful when we need to intercept and properly react
-to (rendering) errors that occur in some sub components. See the section on
-[error handling](#error-handling).
+to (rendering) errors that occur in some sub components. See the page on
+[error handling](error_handling.md).
 
 ### Root Component
 
@@ -548,128 +584,6 @@ with a class object:
 <MyComponent t-att-class="{a: state.flagA, b: state.flagB}" />
 ```
 
-### Event Handling
-
-In a component's template, it is useful to be able to register handlers on DOM
-elements to some specific events. This is what makes a template _alive_. There
-are four different use cases.
-
-1. Register an event handler on a DOM node (_pure_ DOM event)
-2. Register an event handler on a component (_pure_ DOM event)
-3. Register an event handler on a DOM node (_business_ DOM event)
-4. Register an event handler on a component (_business_ DOM event)
-
-A _pure_ DOM event is directly triggered by a user interaction (e.g. a `click`).
-
-```xml
-<button t-on-click="someMethod">Do something</button>
-```
-
-This will be roughly translated in javascript like this:
-
-```js
-button.addEventListener("click", component.someMethod.bind(component));
-```
-
-The suffix (`click` in this example) is simply the name of the actual DOM
-event.
-
-A _business_ DOM event is triggered by a call to `trigger` on a component.
-
-```xml
-<MyComponent t-on-menu-loaded="someMethod" />
-```
-
-```js
- class MyComponent {
-     someWhere() {
-         const payload = ...;
-         this.trigger('menu-loaded', payload);
-     }
- }
-```
-
-The call to `trigger` generates an `OwlEvent`, a subclass of [_CustomEvent_](https://developer.mozilla.org/docs/Web/Guide/Events/Creating_and_triggering_events)
-with an additional attribute `originalComponent` (the component that triggered
-the event). The generated event is of type `menu-loaded` and dispatches it on
-the component's DOM element (`this.el`). The event bubbles and is cancelable.
-The parent component listening to event `menu-loaded` will receive the payload
-in its `someMethod` handler (in the `detail` property of the event), whenever
-the event is triggered.
-
-```js
- class ParentComponent {
-     someMethod(ev) {
-         const payload = ev.detail;
-         ...
-     }
- }
-```
-
-By convention, we use KebabCase for the name of _business_ events.
-
-The `t-on` directive allows to prebind its arguments. For example,
-
-```xml
-<button t-on-click="someMethod(expr)">Do something</button>
-```
-
-Here, `expr` is a valid Owl expression, so it could be `true` or some variable
-from the rendering context.
-
-One can also directly specify inline statements. For example,
-
-```xml
-<button t-on-click="state.counter++">Increment counter</button>
-```
-
-Here, `state` must be defined in the rendering context (typically the component)
-as it will be translated to:
-
-```js
-button.addEventListener("click", () => {
-  context.state.counter++;
-});
-```
-
-Warning: inline expressions are evaluated in the context of the template. This
-means that they can access the component methods and properties. But if they set
-a key, the inline statement will actually not modify the component, but a key in
-a sub scope.
-
-```xml
-<button t-on-click="value = 1">Set value to 1 (does not work!!!)</button>
-<button t-on-click="state.value = 1">Set state.value to 1 (work as expected)</button>
-```
-
-In order to remove the DOM event details from the event handlers (like calls to
-`event.preventDefault`) and let them focus on data logic, _modifiers_ can be
-specified as additional suffixes of the `t-on` directive.
-
-| Modifier   | Description                                                       |
-| ---------- | ----------------------------------------------------------------- |
-| `.stop`    | calls `event.stopPropagation()` before calling the method         |
-| `.prevent` | calls `event.preventDefault()` before calling the method          |
-| `.self`    | calls the method only if the `event.target` is the element itself |
-
-```xml
-<button t-on-click.stop="someMethod">Do something</button>
-```
-
-Note that modifiers can be combined (ex: `t-on-click.stop.prevent`), and that
-the order may matter. For instance `t-on-click.prevent.self` will prevent all
-clicks while `t-on-click.self.prevent` will only prevent clicks on the element
-itself.
-
-Finally, empty handlers are tolerated as they could be defined only to apply
-modifiers. For example,
-
-```xml
-<button t-on-click.stop="">Do something</button>
-```
-
-This will simply stop the propagation of the event.
-
 ### Form Input Bindings
 
 It is very common to need to be able to read the value out of an html `input` (or
@@ -819,75 +733,6 @@ Note that these two examples uses the suffix `ref` to name the reference. This
 is not mandatory, but it is a useful convention, so we do not forget to access
 it with the `el` or `comp` suffix.
 
-### Slots
-
-To make generic components, it is useful to be able for a parent component to _inject_
-some sub template, but still be the owner. For example, a generic dialog component
-will need to render some content, some footer, but with the parent as the
-rendering context.
-
-This is what _slots_ are for.
-
-```xml
-<div t-name="Dialog" class="modal">
-  <div class="modal-title"><t t-esc="props.title"/></div>
-  <div class="modal-content">
-    <t t-slot="content"/>
-  </div>
-  <div class="modal-footer">
-    <t t-slot="footer"/>
-  </div>
-</div>
-```
-
-Slots are defined by the caller, with the `t-set` directive:
-
-```xml
-<div t-name="SomeComponent">
-  <div>some component</div>
-  <Dialog title="Some Dialog">
-    <t t-set="content">
-      <div>hey</div>
-    </t>
-    <t t-set="footer">
-      <button t-on-click="doSomething">ok</button>
-    </t>
-  </Dialog>
-</div>
-```
-
-In this example, the component `Dialog` will render the slots `content` and `footer`
-with its parent as rendering context. This means that clicking on the button
-will execute the `doSomething` method on the parent, not on the dialog.
-
-Default slot: the first element inside the component which is not a named slot will
-be considered the `default` slot. For example:
-
-```xml
-<div t-name="Parent">
-  <Child>
-    <span>some content</span>
-  </Child>
-</div>
-
-<div t-name="Child">
-  <t t-slot="default"/>
-</div>
-```
-
-Slots can define a default content, in case the parent did not define them:
-
-```xml
-<div t-name="Parent">
-  <Child/>
-</div>
-
-<span t-name="Child">
-  <t t-slot="default">default content</t>
-</span>
-<!-- will be rendered as: <div><span>default content</span></div> -->
-```
-
 ### Dynamic sub components
 
 It is not common, but sometimes we need a dynamic component name. In this case,
@@ -933,65 +778,6 @@ component class.
 
 Note that the `t-component` directive can only be used on `<t>` nodes.
 
-### Error Handling
-
-By default, whenever an error occurs in the rendering of an Owl application, we
-destroy the whole application. Otherwise, we cannot offer any guarantee on the
-state of the resulting component tree. It might be hopelessly corrupted, but
-without any user-visible state.
-
-Clearly, it sometimes is a little bit extreme to destroy the application. This
-is why we have a builtin mechanism to handle rendering errors (and errors coming
-from lifecycle hooks): the `catchError` hook.
-
-Whenever the `catchError` lifecycle hook is implemented, all errors coming from
-sub components rendering and/or lifecycle method calls will be caught and given
-to the `catchError` method. This allows us to properly handle the error, and to
-not break the application.
-
-For example, here is how we could implement an `ErrorBoundary` component:
-
-```xml
-<div t-name="ErrorBoundary">
-    <t t-if="state.error">
-        Error handled
-    </t>
-    <t t-else="">
-        <t t-slot="default" />
-    </t>
-</div>
-```
-
-```js
-class ErrorBoundary extends Component {
-  state = useState({ error: false });
-
-  catchError() {
-    this.state.error = true;
-  }
-}
-```
-
-Using the `ErrorBoundary` is then extremely simple:
-
-```xml
-<ErrorBoundary><SomeOtherComponent/></ErrorBoundary>
-```
-
-Note that we need to be careful here: the fallback UI should not throw any
-error, otherwise we risk going into an infinite loop.
-
-Also, it may be useful to know that whenever an error is caught, it is then
-broadcasted to the application by an event on the `qweb` instance. It may be
-useful, for example, to log the error somewhere.
-
-```js
-env.qweb.on("error", null, function(error) {
-  // do something
-  // react to the error
-});
-```
-
 ### Functional Components
 
 Owl does not exactly have functional components. However, there is an extremely
@@ -1003,7 +789,7 @@ template rendered with `props`. In Owl, this can be done by
 simply defining a template, that will access the `props` object:
 
 ```js
-const Welcome = xml`<h1>Hello, {props.name}</h1>`;
+const Welcome = xml`<h1>Hello, <t t-esc="props.name"/></h1>`;
 
 class MyComponent extends Component {
   static template = xml`
@@ -1053,8 +839,8 @@ class RootNode extends Component {
     children: [
       { label: "b" },
       { label: "c", children: [{ label: "d" }, { label: "e" }] },
-      { label: "f", children: [{ label: "g" }] }
-    ]
+      { label: "f", children: [{ label: "g" }] },
+    ],
   };
 }
 ```

doc/reference/concurrency_model.md

@@ -23,7 +23,7 @@ a rendering that is no longer relevant, restart it, reuse it in some cases.
 But even though using concurrency is quite simple (and is the default behaviour),
 asynchrony is difficult, because it introduces an additional dimension that
 vastly increase the complexity of an application. This section will explain
-how Owl manages this complexity, how concuurent rendering works in a general way.
+how Owl manages this complexity, how concurrent rendering works in a general way.
 
 ## Rendering Components
 
@@ -120,7 +120,7 @@ Here is what Owl will do:
      1. hook `willUpdateProps` is called on `D` (async)
      2. template `D` is rerendered
    - component `F` is created:
-     1. hook `willStart` is called on `E` (async)
+     1. hook `willStart` is called on `F` (async)
      2. template `F` is rendered
 
 3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,
@@ -137,7 +137,7 @@ Here is what Owl will do:
 
 Tags are very small helpers to make it easy to write inline templates. There is
 only one currently available tag: `xml`, but we plan to add other tags later,
-such as a `css` tag, which will be used to write [single file components](../tooling.md#single-file-component).
+such as a `css` tag, which will be used to write [single file components](../learning/how_to_write_sfc.md).
 
 ### Asynchronous Rendering
 

doc/reference/config.md

@@ -2,9 +2,10 @@
 
 The Owl framework is designed to work in many situations. However, it is
 sometimes necessary to customize some behaviour. This is done by using the
-global `config` object. It currently has one key:
+global `config` object. It provides two settings:
 
-- [`mode`](#mode).
+- [`mode`](#mode) (default value: `prod`),
+- [`enableTransitions`](#enabletransitions) (default value: `true`).
 
 ## Mode
 
@@ -25,3 +26,19 @@ So, changing this setting is best done at startup.
 
 An important job done by the `dev` mode is to validate props for each component
 creation and update. Also, extra props will cause an error.
+
+## `enableTransitions`
+
+Transitions are usually nice, but they can cause issues in some specific cases,
+such as automated tests. It is uncomfortable having to wait for a transition
+to end before moving to the next step.
+
+To solve this issue, Owl can be configured to ignore the `t-transition` directive.
+To do that, one only needs to set the `enableTransitions` flag to false:
+
+```js
+owl.config.enableTransitions = false;
+```
+
+Note that it suffers from the same drawback as the "dev" mode: all compiled
+templates, if any, will keep their current behaviours.

doc/reference/content.md

@@ -0,0 +1,40 @@
+# 🦉 Owl Content 🦉
+
+Here is a complete visual representation of everything exported by the `owl`
+global object.
+
+For example, `Component` is available at `owl.Component` and `EventBus` is
+exported as `owl.core.EventBus`.
+
+```
+browser
+Component                               misc
+Context                                     AsyncRoot
+QWeb                                        Portal
+mount                                   router
+Store                                       Link
+useState                                    RouteComponent
+config                                      Router
+    mode
+core                                    tags
+    EventBus                                css
+    Observer                                xml
+hooks                                   utils
+    onWillStart                             debounce
+    onMounted                               escape
+    onWillUpdateProps                       loadJS
+    onWillPatch                             loadFile
+    onPatched                               shallowEqual
+    onWillUnmount                           whenReady
+    useContext
+    useState
+    useRef
+    useComponent
+    useEnv
+    useSubEnv
+    useStore
+    useDispatch
+    useGetters
+```
+
+Note that for convenience, the `useState` hook is also exported at the root of the `owl` object.

doc/reference/environment.md

@@ -6,6 +6,7 @@
 - [Setting an Environment](#setting-an-environment)
 - [Using a sub environment](#using-a-sub-environment)
 - [Content of an Environment](#content-of-an-environment)
+- [Special keys](#special-keys)
 
 ## Overview
 
@@ -40,23 +41,22 @@ all templates.
 Whenever a root component `App` is mounted, Owl will setup a valid environment by
 following the next steps:
 
-- take the `env` object defined on `App.env` (if no `env` was explicitely setup,
-  this will be return the empty `env` object defined on `Component`)
+- take the `env` object defined on `App.env` (if no `env` was explicitly setup,
+  this will return the empty `env` object defined on `Component`)
 - if `env.qweb` is not set, then Owl will create a `QWeb` instance.
 
 The correct way to customize an environment is to simply set it up on the root
 component class, before the first component is created:
 
 ```js
-App.env = {
+const env = {
     _t: myTranslateFunction,
     user: {...},
     services: {
         ...
     },
 };
-const app = new App();
-app.mount(document.body);
+mount(App, { target: document.body, env });
 ```
 
 It is also possible to simply share an environment between all root components,
@@ -93,7 +93,7 @@ Some good use cases for additional keys in the environment are:
 
 - some configuration keys,
 - session information,
-- generic services (such as doing rpcs, or accessing local storage).
+- generic services (such as doing rpcs).
 
 Doing it this way means that components are easily testable: we can simply
 create a test environment with mock services.
@@ -112,16 +112,25 @@ async function myEnv() {
     qweb: qweb,
     services: {
       localStorage: localStorage,
-      rpc: rpc
+      rpc: rpc,
     },
     debug: false,
-    inMobileMode: true
+    inMobileMode: true,
   };
 }
 
 async function start() {
-  App.env = await myEnv();
-  const app = new App();
-  await app.mount(document.body);
+  const env = await myEnv();
+  mount(App, { target: document.body, env });
 }
 ```
+
+## Special Keys
+
+There are two special key/value added by Owl if not provided in the environment:
+the `QWeb` instance and a `browser` object:
+
+- `qweb` will be set to an empty `QWeb` instance. This is absolutely necessary
+  for Owl to be able to render anything
+- `browser`: this is an object that contains some common access points to the
+  browser methods with a side effect. See [browser](browser.md) for more information. Note that the browser object will be removed from the environment in Owl 2.0.

doc/reference/error_handling.md

@@ -0,0 +1,81 @@
+# 🦉 Error Handling 🦉
+
+## Content
+
+- [Overview](#overview)
+- [Example](#example)
+- [Reference](#reference)
+
+## Overview
+
+By default, whenever an error occurs in the rendering of an Owl application, we
+destroy the whole application. Otherwise, we cannot offer any guarantee on the
+state of the resulting component tree. It might be hopelessly corrupted, but
+without any user-visible state.
+
+Clearly, it sometimes is a little bit extreme to destroy the application. This
+is why we have a builtin mechanism to handle rendering errors (and errors coming
+from lifecycle hooks): the `catchError` hook.
+
+## Example
+
+For example, here is how we could implement an `ErrorBoundary` component:
+
+```xml
+<div t-name="ErrorBoundary">
+    <t t-if="state.error">
+        Error handled
+    </t>
+    <t t-else="">
+        <t t-slot="default" />
+    </t>
+</div>
+```
+
+```js
+class ErrorBoundary extends Component {
+  state = useState({ error: false });
+
+  catchError() {
+    this.state.error = true;
+  }
+}
+```
+
+Using the `ErrorBoundary` is then extremely simple:
+
+```xml
+<ErrorBoundary><SomeOtherComponent/></ErrorBoundary>
+```
+
+Note that we need to be careful here: the fallback UI should not throw any
+error, otherwise we risk going into an infinite loop (also, see the page on
+[slots](slots.md) for more information on the `t-slot` directive).
+
+## Reference
+
+Whenever the `catchError` lifecycle hook is implemented, all errors coming from
+sub components rendering and/or lifecycle method calls will be caught and given
+to the `catchError` method. This allows us to properly handle the error, and to
+not break the application.
+
+There are important things to know:
+
+- If an error that occured in the internal rendering cycle is not caught, then
+  Owl will destroy the full application. This is done on purpose, because Owl
+  cannot guarantee that the state is not corrupted from this point on.
+
+- errors coming from event handlers are NOT managed by `catchError` or any other
+  owl mechanism. This is up to the application developer to properly recover
+  from an error
+
+Also, it may be useful to know that whenever an error is caught, it is then
+broadcasted to the application by an event on the `qweb` instance. It may be
+useful, for example, to log the error somewhere.
+
+```js
+env.qweb.on("error", null, function (error) {
+  // do something
+  // react to the error
+});
+```

doc/reference/event_bus.md

@@ -7,7 +7,7 @@ triggering events, and callbacks.
 ```js
 const bus = new owl.core.EventBus();
 
-bus.on("some-event", null, function(...args) {
+bus.on("some-event", null, function (...args) {
   console.log(...args);
 });
 

doc/reference/event_handling.md

@@ -0,0 +1,151 @@
+# 🦉 Event Handling 🦉
+
+## Content
+
+- [Event Handling](#event-handling)
+- [Business DOM Events](#business-dom-events)
+- [Inline Event Handlers](#inline-event-handlers)
+- [Modifiers](#modifiers)
+
+## Event Handling
+
+In a component's template, it is useful to be able to register handlers on DOM
+elements to some specific events. This is what makes a template _alive_. There
+are four different use cases.
+
+1. Register an event handler on a DOM node (_pure_ DOM event)
+2. Register an event handler on a component (_pure_ DOM event)
+3. Register an event handler on a DOM node (_business_ DOM event)
+4. Register an event handler on a component (_business_ DOM event)
+
+A _pure_ DOM event is directly triggered by a user interaction (e.g. a `click`).
+
+```xml
+<button t-on-click="someMethod">Do something</button>
+```
+
+This will be roughly translated in javascript like this:
+
+```js
+button.addEventListener("click", component.someMethod.bind(component));
+```
+
+The suffix (`click` in this example) is simply the name of the actual DOM
+event.
+
+## Business DOM Events
+
+A _business_ DOM event is triggered by a call to `trigger` on a component.
+
+```xml
+<MyComponent t-on-menu-loaded="someMethod" />
+```
+
+```js
+ class MyComponent {
+     someWhere() {
+         const payload = ...;
+         this.trigger('menu-loaded', payload);
+     }
+ }
+```
+
+The call to `trigger` generates an `OwlEvent`, a subclass of [_CustomEvent_](https://developer.mozilla.org/docs/Web/Guide/Events/Creating_and_triggering_events)
+with an additional attribute `originalComponent` (the component that triggered
+the event). The generated event is of type `menu-loaded` and dispatches it on
+the component's DOM element (`this.el`). The event bubbles and is cancelable.
+The parent component listening to event `menu-loaded` will receive the payload
+in its `someMethod` handler (in the `detail` property of the event), whenever
+the event is triggered.
+
+```js
+ class ParentComponent {
+     someMethod(ev) {
+         const payload = ev.detail;
+         ...
+     }
+ }
+```
+
+By convention, we use KebabCase for the name of _business_ events.
+
+The `t-on` directive allows to prebind its arguments. For example,
+
+```xml
+<button t-on-click="someMethod(expr)">Do something</button>
+```
+
+Here, `expr` is a valid Owl expression, so it could be `true` or some variable
+from the rendering context.
+
+### Type Hinting
+
+Note that if you work with Typescript, the `trigger` method is generic on the type of the payload.
+
+You can then describe the type of the event, so you will see typing errors...
+
+```typescript
+this.trigger<MyCustomPayload>("my-custom-event", payload);
+```
+
+```typescript
+myCustomEventHandler(ev: OwlEvent<MyCustomPayload>) { ... }
+```
+
+## Inline Event Handlers
+
+One can also directly specify inline statements. For example,
+
+```xml
+<button t-on-click="state.counter++">Increment counter</button>
+```
+
+Here, `state` must be defined in the rendering context (typically the component)
+as it will be translated to:
+
+```js
+button.addEventListener("click", () => {
+  context.state.counter++;
+});
+```
+
+Warning: inline expressions are evaluated in the context of the template. This
+means that they can access the component methods and properties. But if they set
+a key, the inline statement will actually not modify the component, but a key in
+a sub scope.
+
+```xml
+<button t-on-click="value = 1">Set value to 1 (does not work!!!)</button>
+<button t-on-click="state.value = 1">Set state.value to 1 (work as expected)</button>
+```
+
+## Modifiers
+
+In order to remove the DOM event details from the event handlers (like calls to
+`event.preventDefault`) and let them focus on data logic, _modifiers_ can be
+specified as additional suffixes of the `t-on` directive.
+
+| Modifier   | Description                                                                                                              |
+| ---------- | ------------------------------------------------------------------------------------------------------------------------ |
+| `.stop`    | calls `event.stopPropagation()` before calling the method                                                                |
+| `.prevent` | calls `event.preventDefault()` before calling the method                                                                 |
+| `.self`    | calls the method only if the `event.target` is the element itself                                                        |
+| `.capture` | bind the event handler in [capture](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener) mode. |
+
+```xml
+<button t-on-click.stop="someMethod">Do something</button>
+```
+
+Note that modifiers can be combined (ex: `t-on-click.stop.prevent`), and that
+the order may matter. For instance `t-on-click.prevent.self` will prevent all
+clicks while `t-on-click.self.prevent` will only prevent clicks on the element
+itself.
+
+Finally, empty handlers are tolerated as they could be defined only to apply
+modifiers. For example,
+
+```xml
+<button t-on-click.stop="">Do something</button>
+```
+
+This will simply stop the propagation of the event.

doc/reference/hooks.md

@@ -17,9 +17,12 @@
   - [`useContext`](#usecontext)
   - [`useRef`](#useref)
   - [`useSubEnv`](#usesubenv)
+  - [`useExternalListener`](#useexternallistener)
   - [`useStore`](#usestore)
   - [`useDispatch`](#usedispatch)
   - [`useGetters`](#usegetters)
+  - [`useComponent`](#usecomponent)
+  - [`useEnv`](#useenv)
   - [Making customized hooks](#making-customized-hooks)
 
 ## Overview
@@ -128,7 +131,7 @@ class SomeComponent extends Component {
 ### One rule
 
 There is only one rule: every hook for a component has to be called in the
-constructor (or in class fields):
+constructor, in the _setup_ method, or in class fields:
 
 ```js
 // ok
@@ -144,6 +147,13 @@ class SomeComponent extends Component {
   }
 }
 
+// also ok
+class SomeComponent extends Component {
+  setup() {
+    this.state = useState({ value: 0 });
+  }
+}
+
 // not ok: this is executed after the constructor is called
 class SomeComponent extends Component {
   async willStart() {
@@ -258,7 +268,7 @@ function useLoader() {
   }
 
   onWillStart(() => updateRecord(component.props.id));
-  onWillUpdateProps(nextProps => updateRecord(nextProps.id));
+  onWillUpdateProps((nextProps) => updateRecord(nextProps.id));
 
   return record;
 }
@@ -354,6 +364,17 @@ will be added to the parent environment. Note that it will extend, not replace
 the parent environment. And of course, the parent environment will not be
 affected.
 
+### `useExternalListener`
+
+The `useExternalListener` hook helps solve a very common problem: adding and removing
+a listener on some target whenever a component is mounted/unmounted. For example,
+a dropdown menu (or its parent) may need to listen to a `click` event on `window`
+to be closed:
+
+```js
+useExternalListener(window, "click", this.closeMenu);
+```
+
 ### `useStore`
 
 The `useStore` hook is the entry point for a component to connect to the store.
@@ -369,6 +390,16 @@ The `useDispatch` hook is the way for components to get a reference to the store
 The `useGetters` hook is the way for components to get a reference to the store
 getters. See the [store documentation](store.md) for more information.
 
+### `useComponent`
+
+The `useComponent` hook is useful as a building block for some customized hooks,
+that may need a reference to the component calling them.
+
+### `useEnv`
+
+The `useEnv` hook is useful as a building block for some customized hooks,
+that may need a reference to the env of the component calling them.
+
 ### Making customized hooks
 
 Hooks are a wonderful way to organize the code of a complex component by feature
@@ -423,13 +454,11 @@ not the solution to every problem.
 
   ```js
   function useRouter() {
-    return Component.current.env.router;
+    const env = useEnv();
+    return env.router;
   }
   ```
 
   This means that we give control to the application developer to create the
   router, which is good, so they can set it up, subclass it, ... And then, to
   test our components, we can just add a mock router in the environment.
-
-Note: the code above makes use of the `Component.current` property. This is the
-way hooks are able to get a reference to the component currently being created.

doc/reference/misc.md

@@ -18,7 +18,7 @@ for modals (as in `bootstrap-modal`).
 ### Usage
 
 The content it will teleport is defined within the `<Portal>` node and
-internally uses the `default` [Slot](component.md#slots).
+internally uses the `default` [Slot](slots.md).
 
 This slot must contain only **one** node, which in turn can have as many children as necessary.
 
@@ -43,7 +43,7 @@ workflow to help the user put in some data, which it could use later on.
 JavaScript:
 
 ```js
-const { Component } = owl;
+const { Component, mount } = owl;
 const { Portal } = owl.misc;
 
 class TeleportedComponent extends Component {}
@@ -51,8 +51,7 @@ class App extends Component {
   static components = { Portal, TeleportedComponent };
 }
 
-const app = new App();
-app.mount(document.body);
+mount(App, { target: document.body });
 ```
 
 XML:
@@ -95,7 +94,7 @@ The teleported piece is updated as any other `Component`'s DOM and in the same s
 Namely the teleported piece will be updated in function of its parents components, and patched as
 a normal child.
 
-The [_business_ events](component.md#event-handling) triggered by a child component will be stopped
+The [_business_ events](event_handling.md#business-dom-events) triggered by a child component will be stopped
 to not bubble outside of the `target`. They will, on the other hand, be re-directed onto the
 `Portal`'s root node and bubble up the DOM as if it were triggered by a regular child component.
 

doc/reference/mounting.md

@@ -0,0 +1,60 @@
+# 🦉 Mounting an application 🦉
+
+## Content
+
+- [Overview](#overview)
+- [API](#api)
+
+## Overview
+
+Mounting an Owl application is done by using the `mount` method (available in
+`owl.mount` if you are using the iife build, or it can be directly imported
+from `owl` if you are using a module system):
+
+```js
+const mount = { owl }; // if owl is available as an object
+
+const env = { ... };
+const app = await mount(MyComponent, { target: document.body, env });
+```
+
+Another example:
+
+```js
+const config = {
+  env: ...,
+  props: ...,
+  target: document.body,
+  position: "self",
+};
+const app = await mount(App, config);
+```
+
+A common way to initialize an application is to first setup an environment,
+then to call the `mount` method.
+
+## API
+
+Mount takes two parameters:
+
+- `C`, which should be a component class (NOT instance),
+- `params`, which is an object with the following keys:
+  - `target (HTMLElement | DocumentFragment)`: the target of the mount operation
+  - `env (optional, Env)` an environment
+  - `position (optional, "first-child" | "last-child" | "self")` the position
+    where it should be mounted (see below for more informations)
+  - `props (optional, any)`: some initial values that are given as props. Useful
+    when the root component is configurable, or when testing sub components
+
+Here are the various positions supported by Owl:
+
+- `first-child`: with this option, the component will be prepended inside the target,
+- `last-child` (default value): with this option, the component will be
+  appended in the target element,
+- `self`: the target will be used as the root element for the component. This
+  means that the target has to be an HTMLElement (and not a document fragment).
+  In this situation, it is possible that the component cannot be unmounted. For
+  example, if its target is `document.body`.
+
+The `mount` method returns a promise that resolves to the instance of the created
+component.

doc/reference/observer.md

@@ -15,7 +15,7 @@ use cases, there is no need to directly instantiate an observer.
 For example, this code will display `update` in the console:
 
 ```javascript
-const observer = new owl.Observer();
+const observer = new owl.core.Observer();
 observer.notifyCB = () => console.log("update");
 const obj = observer.observe({ a: { b: 1 } });
 
@@ -39,14 +39,14 @@ is incremented every time the value is observed. Sometimes, it can be useful
 to obtain that number:
 
 ```js
-const observer = new owl.Observer();
+const observer = new owl.core.Observer();
 const obj = observer.observe({ a: { b: 1 } });
 
-observer.deepRevNumber(obj.a); // 1
+observer.revNumber(obj.a); // 1
 obj.a.b = 2;
 
-observer.deepRevNumber(obj.a); // 2
+observer.revNumber(obj.a); // 2
 ```
 
-The `deepRevNumber` can also return 0, which indicates that the value is not
+The `revNumber` can also return 0, which indicates that the value is not
 observed.

doc/reference/props.md

@@ -18,7 +18,7 @@ class Child extends Component {
 }
 
 class Parent extends Component {
-  static template = xml`<div><ComponentA a="state.a" b="'string'"/></div>`;
+  static template = xml`<div><Child a="state.a" b="'string'"/></div>`;
   static components = { Child };
   state = useState({ a: "fromparent" });
 }

doc/reference/props_validation.md

@@ -30,7 +30,7 @@ class ComponentB extends owl.Component {
     count: {type: Number},
     messages: {
       type: Array,
-      element: {type: Object, shape: {id: Boolean, text: 'string' }
+      element: {type: Object, shape: {id: Boolean, text: String }
     },
    date: Date,
    combinedVal: [Number, Boolean]

doc/reference/qweb_engine.md

@@ -61,7 +61,7 @@ Its API is quite simple:
   ```
 
 - **`render(name, context, extra)`**: renders a template. This returns a `vnode`,
-  which is a virtual representation of the DOM (see [vdom doc](../architecture/vdom.md)).
+  which is a virtual representation of the DOM (see [vdom doc](../miscellaneous/vdom.md)).
 
   ```js
   const vnode = qweb.render("App", component);
@@ -114,9 +114,9 @@ For example:
 const translations = {
   hello: "bonjour",
   yes: "oui",
-  no: "non"
+  no: "non",
 };
-const translateFn = str => translations[str] || str;
+const translateFn = (str) => translations[str] || str;
 
 const qweb = new QWeb({ translateFn });
 ```

doc/reference/qweb_templating_language.md

@@ -13,8 +13,11 @@
   - [Setting Variables](#setting-variables)
   - [Conditionals](#conditionals)
   - [Dynamic Attributes](#dynamic-attributes)
+  - [Dynamic Class Attribute](#dynamic-class-attribute)
+  - [Dynamic Tag Names](#dynamic-tag-names)
   - [Loops](#loops)
   - [Rendering Sub Templates](#rendering-sub-templates)
+  - [Dynamic Sub Templates](#dynamic-sub-templates)
   - [Translations](#translations)
   - [Debugging](#debugging)
 
@@ -71,10 +74,11 @@ needs. Here is a list of all Owl specific directives:
 | `t-component`, `t-props` | [Defining a sub component](component.md#composition)                            |
 | `t-ref`                  | [Setting a reference to a dom node or a sub component](component.md#references) |
 | `t-key`                  | [Defining a key (to help virtual dom reconciliation)](#loops)                   |
-| `t-on-*`                 | [Event handling](component.md#event-handling)                                   |
+| `t-on-*`                 | [Event handling](event_handling.md)                                             |
 | `t-transition`           | [Defining an animation](animations.md#css-transitions)                          |
-| `t-slot`                 | [Rendering a slot](component.md#slots)                                          |
+| `t-slot`                 | [Rendering a slot](slots.md)                                                    |
 | `t-model`                | [Form input bindings](component.md#form-input-bindings)                         |
+| `t-tag`                  | [Rendering nodes with dynamic tag name](#dynamic-tag-names)                     |
 
 ## Reference
 
@@ -323,6 +327,40 @@ values) or a pair `[key, value]`. For example:
 <div t-att="['a', 'b']"/> <!-- <div a="b"></div> -->
 ```
 
+### Dynamic class attribute
+
+For convenience, Owl supports a special case for the `t-att-class` case: one can
+use an object with keys describing the classes, and values boolean value denoting
+if the class is or is not present:
+
+```xml
+<div t-att-class="{'a': true, 'b': true}"/> <!-- result: <div class="a b"></div> -->
+
+<div t-att-class="{'a b': true, 'c': true}"/> <!-- result: <div class="a b c"></div> -->
+```
+
+Note that it can be combined with normal class attribute:
+
+```xml
+<div class="a" t-att-class="{'b': true}"/> <!-- result: <div class="a b"></div> -->
+```
+
+### Dynamic tag names
+
+When writing generic components or templates, the specific concrete tag for an
+HTML element is not known yet. In those situations, the `t-tag` directive is
+useful. It simply evaluates dynamically an expression to use as a tag name. The
+template:
+
+```xml
+<t t-tag="tag">
+    <span>content</span>
+</t>
+```
+
+will be rendered as `<div><span>content</span></div>` if the `tag` context key
+is set to `div`.
+
 ### Loops
 
 QWeb has an iteration directive `t-foreach` which take an expression returning the
@@ -452,6 +490,17 @@ are all equivalent:
 
 If there is no `t-key` directive, Owl will use the index as a default key.
 
+Note: the `t-foreach` directive only accepts arrays (lists) or objects. It does
+not work with other iterables, such as `Set`. However, it is only a matter of
+using the `...` javascript operator. For example:
+
+```xml
+<t t-foreach="...items" t-as="item">...</t>
+```
+
+The `...` operator will convert the `Set` (or any other iterables) into a list,
+which will work with Owl QWeb.
+
 ### Rendering Sub Templates
 
 QWeb templates can be used for top level rendering, but they can also be used
@@ -509,6 +558,22 @@ This can be used to define variables scoped to a sub template:
 <!-- "var" does not exist here -->
 ```
 
+### Dynamic sub templates
+
+The `t-call` directive can also be used to dynamically call a sub template,
+using string interpolation. For example:
+
+```xml
+<div t-name="main-template">
+    <t t-call="{{template}}">
+        <em>content</em>
+    </t>
+</div>
+```
+
+Here, the name of the template is obtained from the `template` value in the
+template rendering context.
+
 ### Translations
 
 By default, QWeb specify that templates should be translated. If this behaviour
@@ -532,7 +597,7 @@ The javascript QWeb implementation provides two useful debugging directives:
 
 ```xml
 <t t-if="a_test">
-    <t t-debug="">
+    <t t-debug=""/>
 </t>
 ```
 

doc/reference/slots.md

@@ -0,0 +1,111 @@
+# 🦉 Slots 🦉
+
+## Content
+
+- [Overview](#overview)
+- [Example](#example)
+- [Reference](#reference)
+
+## Overview
+
+Owl is a template based component system. There is therefore a need to be able
+to make generic components. For example, imagine a generic `Dialog`
+component, which is able to display some arbitrary content.
+
+Obviously, we want to use this component everywhere in our application, to
+display various different content. The `Dialog` component is technically the
+owner of its content, but is only a container. The user of the `Dialog` is
+the component that want to _inject_ something inside the `Dialog`. This is
+exactly what slots are for.
+
+## Example
+
+To make generic components, it is useful to be able for a parent component to _inject_
+some sub template, but still be the owner. For example, a generic dialog component
+will need to render some content, some footer, but with the parent as the
+rendering context.
+
+Slots are inserted with the `t-slot` directive:
+
+```xml
+<div t-name="Dialog" class="modal">
+  <div class="modal-title"><t t-esc="props.title"/></div>
+  <div class="modal-content">
+    <t t-slot="content"/>
+  </div>
+  <div class="modal-footer">
+    <t t-slot="footer"/>
+  </div>
+</div>
+```
+
+Slots are defined by the caller, with the `t-set-slot` directive:
+
+```xml
+<div t-name="SomeComponent">
+  <div>some component</div>
+  <Dialog title="'Some Dialog'">
+    <t t-set-slot="content">
+      <div>hey</div>
+    </t>
+    <t t-set-slot="footer">
+      <button t-on-click="doSomething">ok</button>
+    </t>
+  </Dialog>
+</div>
+```
+
+In this example, the component `Dialog` will render the slots `content` and `footer`
+with its parent as rendering context. This means that clicking on the button
+will execute the `doSomething` method on the parent, not on the dialog.
+
+Note: Owl previously used the `t-set` directive to define the content of a slot.
+This is deprecated and should no longer be used in new code.
+
+## Reference
+
+### Default Slot
+
+The first element inside the component which is not a named slot will
+be considered the `default` slot. For example:
+
+```xml
+<div t-name="Parent">
+  <Child>
+    <span>some content</span>
+  </Child>
+</div>
+
+<div t-name="Child">
+  <t t-slot="default"/>
+</div>
+```
+
+### Default content
+
+Slots can define a default content, in case the parent did not define them:
+
+```xml
+<div t-name="Parent">
+  <Child/>
+</div>
+
+<span t-name="Child">
+  <t t-slot="default">default content</t>
+</span>
+<!-- will be rendered as: <div><span>default content</span></div> -->
+```
+
+Rendering context: the content of the slots is actually rendered with the
+rendering context corresponding to where it was defined, not where it is
+positioned. This allows the user to define event handlers that will be bound
+to the correct component (usually, the grandparent of the slot content).
+
+### Dynamic Slots
+
+The `t-slot` directive is actually able to use any expressions, using string
+interplolation:
+
+```xml
+ <t t-slot="{{current}}" />
+```

doc/reference/store.md

@@ -40,14 +40,14 @@ const actions = {
     state.todos.push({
       id: state.nextId++,
       message,
-      isCompleted: false
+      isCompleted: false,
     });
-  }
+  },
 };
 
 const state = {
   todos: [],
-  nextId: 1
+  nextId: 1,
 };
 
 const store = new owl.Store({ state, actions });
@@ -90,7 +90,7 @@ const config = {
   state,
   actions,
   getters,
-  env
+  env,
 };
 const store = new Store(config);
 ```
@@ -110,7 +110,7 @@ const actions = {
     } catch (e) {
       state.loginState = "error";
     }
-  }
+  },
 };
 ```
 
@@ -144,7 +144,7 @@ const actions = {
     state.recordId = recordId;
     const data = await doSomeRPC("/read/", recordId);
     state.recordData = data;
-  }
+  },
 };
 ```
 
@@ -159,7 +159,7 @@ const actions = {
     const data = await doSomeRPC("/read/", recordId);
     state.recordId = recordId;
     state.recordData = data;
-  }
+  },
 };
 ```
 
@@ -187,14 +187,14 @@ transform the data contained in the store.
 ```js
 const getters = {
   getPost({ state }, id) {
-    const post = state.posts.find(p => p.id === id);
-    const author = state.authors.find(a => a.id === post.id);
+    const post = state.posts.find((p) => p.id === id);
+    const author = state.authors.find((a) => a.id === post.id);
     return {
       id,
       author,
-      content: post.content
+      content: post.content,
     };
-  }
+  },
 };
 
 // somewhere else
@@ -208,7 +208,11 @@ Note that getters are not cached.
 ### Connecting a Component
 
 At some point, we need a way to interact with the store from a component. This
-can be done with the help of the three store hooks:
+means that the component needs a reference to the store. By default, it looks
+for it in the `env.store` key. However, this can be configured with the `useStore`
+hook.
+
+Every component-store interactions are done with the help of the three store hooks:
 
 - [`useStore`](#usestore) to subscribe a component to some part of the store state,
 - [`useDispatch`](#usedispatch) to get a reference to a dispatch function,
@@ -220,20 +224,28 @@ Assume we have this store:
 const actions = {
   increment({ state }, val) {
     state.counter.value += val;
-  }
+  },
 };
 
 const state = {
-  counter: { value: 0 }
+  counter: { value: 0 },
 };
 const store = new owl.Store({ state, actions });
 ```
 
+To make it accessible to the complete application, we will put it in the
+environment:
+
+```js
+// in this example, the root component is App
+App.env.store = store;
+```
+
 A counter component can then select this value and dispatch an action like this:
 
 ```js
 class Counter extends Component {
-  counter = useStore(state => state.counter);
+  counter = useStore((state) => state.counter);
   dispatch = useDispatch();
 }
 

doc/reference/tags.md

@@ -4,16 +4,19 @@
 
 - [Overview](#overview)
 - [`xml` tag](#xml-tag)
+- [`css` tag](#css-tag)
 
 ## Overview
 
-Tags are very small helpers to make it easy to write inline templates. There is
-only one currently available tag: `xml`, but we plan to add other tags later,
-such as a `css` tag, which will be used to write [single file components](../tooling.md#single-file-component).
+Tags are very small helpers intended to make it easy to write inline templates
+or styles. There are currently two tags: `css` and `xml`. With these functions,
+it is possible to write [single file components](../learning/how_to_write_sfc.md).
 
 ## XML tag
 
-Without tags, creating a standalone component would look like this:
+The `xml` tag is certainly the most useful tag. It is used to define an inline
+QWeb template for a component. Without tags, creating a standalone component
+would look like this:
 
 ```js
 import { Component } from 'owl'
@@ -52,3 +55,130 @@ class MyComponent extends Component {
     ...
 }
 ```
+
+## CSS tag
+
+The CSS tag is useful to define a css stylesheet in the javascript file:
+
+```js
+class MyComponent extends Component {
+  static template = xml`
+        <div class="my-component">some template</div>
+    `;
+  static style = css`
+    .my-component {
+      color: red;
+    }
+  `;
+}
+```
+
+The `css` tag registers internally the css information. Then, whenever the first
+instance of the component is created, will add a `<style>` tag to the document
+`<head>`.
+
+Note that to make it more useful, like other css preprocessors, the `css` tag
+accepts a small extension of the css specification: css scopes can be nested,
+and the rules will then be expanded by the `css` helper:
+
+```scss
+.my-component {
+  display: block;
+  .sub-component h {
+    color: red;
+  }
+}
+```
+
+will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component .sub-component h {
+  color: red;
+}
+```
+
+This extension brings another useful feature: the `&` selector which refers to
+the parent selector. For example, we want our component to be red when hovered.
+We would like to write something like:
+
+```scss
+.my-component {
+  display: block;
+  :hover {
+    color: red;
+  }
+}
+```
+
+but it will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component :hover {
+  color: red;
+}
+```
+
+The `&` selector can be used to solve this problem:
+
+```scss
+.my-component {
+  display: block;
+  &:hover {
+    color: red;
+  }
+}
+```
+
+will be formatted as:
+
+```css
+.my-component {
+  display: block;
+}
+.my-component:hover {
+  color: red;
+}
+```
+
+Now, there is no additional processing done by the `css` tag. However, since it
+is done in javascript at runtime, we actually have more power. For example:
+
+1. sharing values between javascript and css:
+
+```js
+import { theme } from "./theme";
+
+class MyComponent extends Component {
+  static template = xml`<div class="my-component">...</div>`;
+  static style = css`
+    .my-component {
+      color: ${theme.MAIN_COLOR};
+      background-color: ${theme.SECONDARY_color};
+    }
+  `;
+}
+```
+
+2. scoping rules to the current component:
+
+```js
+import { generateUUID } from "./utils";
+
+const uuid = generateUUID();
+
+class MyComponent extends Component {
+  static template = xml`<div data-o-${uuid}="">...</div>`;
+  static style = css`
+    [data-o-${uuid}] {
+      color: red;
+    }
+  `;
+}
+```

doc/reference/utils.md

@@ -19,20 +19,20 @@ not ready yet, resolved directly otherwise). If called with a callback as
 argument, it executes it as soon as the DOM ready (or directly).
 
 ```js
-Promise.all([loadFile("templates.xml"), owl.utils.whenReady()]).then(function([templates]) {
+Promise.all([loadFile("templates.xml"), owl.utils.whenReady()]).then(function ([templates]) {
   const qweb = new owl.QWeb({ templates });
-  const app = new App({ qweb });
-  app.mount(document.body);
+  const env = { qweb };
+  await mount(App, { env, target: document.body });
 });
 ```
 
 or alternatively:
 
 ```js
-owl.utils.whenReady(function() {
+owl.utils.whenReady(function () {
   const qweb = new owl.QWeb();
-  const app = new App({ qweb });
-  app.mount(document.body);
+  const env = { qweb };
+  await mount(App, { env, target: document.body });
 });
 ```
 

doc/tooling.md

@@ -1,106 +0,0 @@
-# 🦉 Tooling 🦉
-
-## Content
-
-- [Overview](#overview)
-- [Playground](#playground)
-- [Benchmarks](#benchmarks)
-- [Single File Component](#single-file-component)
-- [Debugging Script](#debugging-script)
-
-## Overview
-
-To help work with/improve/learn OWL, there are a few extras tools/settings.
-
-- development mode: enable better error reporting for the developer
-- a playground application: a space to experiment and learn Owl.
-- a benchmarks application: allow comparison with a few common frameworks
-
-The two applications are available in the `tools/` folder, and can be accessed
-by using a static http server. A simple python
-server is available in `server.py`. There is also a npm script to start it:
-`npm run tools` (and its version with a watcher: `npm run tools:watch`).
-
-## Playground
-
-The playground is an important application designed to help learning and
-experimenting with Owl. The last published version of Owl can be tested [online](https://odoo.github.io/owl/playground/).
-
-It is an application similar to `jsFiddle`, but specialized for Owl: there are
-three tabs (`js`, `css` and `xml`), and a simple button `Run` to execute that
-code in an iframe.
-
-## Benchmarks
-
-Note: This is more an internal tool, useful for people working on Owl.
-
-The benchmarks application is a very small application, implemented in different
-frameworks, and in different versions of Owl. This is a simple internal tool,
-useful to compare various performance metrics on some tasks.
-
-## Single File Component
-
-It is very useful to group code by feature instead of by type of file. It makes
-it easier to scale application to larger size.
-
-To do so, Owl currently has a small helper that makes it easy to define a
-template inside a javascript (or typescript) file: the [`xml`](reference/tags.md#xml-tag)
-helper. With this, a template is automatically registered to [QWeb](reference/qweb_engine.md).
-
-This means that the template and the javascript code can be defined in the same
-file. It is not currently possible to add css to the same file, but Owl may
-get a `css` tag helper later.
-
-```js
-const { Component } = owl;
-const { xml } = owl.tags;
-
-// -----------------------------------------------------------------------------
-// TEMPLATE
-// -----------------------------------------------------------------------------
-const TEMPLATE = xml/* xml */ `
-	<div class="main two-columns">
-		<Sidebar/>
-		<Content />
-	</div>`;
-
-// -----------------------------------------------------------------------------
-// CODE
-// -----------------------------------------------------------------------------
-class MyComponent extends Component {
-  static template = TEMPLATE;
-  static components = { Sidebar, Content };
-
-  // rest of component...
-}
-```
-
-Note that the above example has an inline xml comment, just after the `xml` call.
-This is useful for some editor plugins, such as the VS Code addon
-`Comment tagged template`, which, if installed, add syntax highlighting to the
-content of the template string.
-
-## Debugging Script
-
-## Debugging
-
-Non trivial applications become quickly more difficult to understand. It is then
-useful to have a solid understanding of what is going on. To help with that,
-logging useful information is extremely valuable. There is a [javascript file](../tools/debug.js) which can be evaluated in an application.
-
-Once it is executed, it will log a lot of information on each component main hooks. The following code is a minified version to make it easier to copy/paste:
-
-```
-function debugOwl(t,n){let e,o="[OWL_DEBUG]";function s(t){let n=JSON.stringify(t||{});return n.length>200&&(n=n.slice(0,200)+"..."),n}if(Object.defineProperty(t.Component,"current",{get:()=>e,set(i){e=i;const r=i.constructor.name;if(n.componentBlackList&&n.componentBlackList.test(r))return;if(n.componentWhiteList&&!n.componentWhiteList.test(r))return;let l;Object.defineProperty(e,"__owl__",{get:()=>l,set(e){!function(e,i,r){let l=`${i}<id=${r}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!n.methodBlackList||!n.methodBlackList.includes(t))&&!(n.methodWhiteList&&!n.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${s(e.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${s(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=e.__render.bind(e);e.__render=function(...t){c("rendering template"),d(...t)};const h=e.render.bind(e);e.render=function(...t){const n=e.__owl__;let o="render";return n.isMounted||n.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=e.mount.bind(e);e.mount=function(...t){return c("mount"),p(...t)}}(i,r,(l=e).id)}})}}),n.logScheduler){let n=t.Component.scheduler.start,e=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),n.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),e.call(this)}}if(n.logStore){let n=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...e){return console.log(`${o} store: action '${t}' dispatched. Payload: '${s(e)}'`),n.call(this,t,...e)}}}
-debugOwl(owl, {
-  // componentBlackList: /App/,  // regexp
-  // componentWhiteList: /SomeComponent/, // regexp
-  // methodBlackList: ["mounted"], // list of method names
-  // methodWhiteList: ["willStart"], // list of method names
-  logScheduler: false,  // display/mute scheduler logs
-  logStore: true,     // display/mute store logs
-});
-```
-
-Note that it is certainly useful to run this code at some point in an application,
-just to get a feel of what each user action implies, for the framework.

package.json

@@ -1,54 +1,65 @@
 {
-  "name": "owl-framework",
-  "version": "1.0.0-beta2",
+  "name": "@odoo/owl",
+  "version": "1.4.9",
   "description": "Odoo Web Library (OWL)",
-  "main": "src/index.ts",
+  "main": "dist/owl.cjs.js",
+  "browser": "dist/owl.iife.js",
+  "module": "dist/owl.es.js",
+  "types": "dist/types/index.d.ts",
+  "files": [
+    "dist"
+  ],
   "engines": {
-    "node": ">=10.15.3"
+    "node": ">=12.18.3"
   },
   "scripts": {
-    "build:js": "tsc --target esnext --module es6 --outDir dist/owl",
     "build:bundle": "rollup -c",
-    "build": "npm run build:js && npm run build:bundle",
-    "buildcommonjs": "npm run build:js && npm run build:bundle -- -f cjs",
-    "minify": "uglifyjs dist/owl.js -o dist/owl.min.js --compress --mangle",
+    "build": "npm run build:bundle",
     "test": "jest",
     "test:watch": "jest --watch",
     "tools:serve": "python3 tools/server.py || python tools/server.py",
     "tools": "npm run build && npm run tools:serve",
     "pretools:watch": "npm run build",
     "tools:watch": "npm-run-all  --parallel tools:serve \"build:* -- --watch\"",
-    "prettier": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --write"
+    "prettier": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --write",
+    "check-formatting": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --check",
+    "publish": "npm run build && npm publish",
+    "release": "node tools/release.js"
   },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/odoo/owl.git"
   },
   "author": "Odoo",
-  "license": "LGPL",
+  "license": "LGPL-3.0-only",
   "bugs": {
     "url": "https://github.com/odoo/owl/issues"
   },
   "homepage": "https://github.com/odoo/owl#readme",
-  "dependencies": {},
   "devDependencies": {
-    "@types/jest": "^23.3.12",
+    "@types/jest": "^27.0.1",
+    "@types/node": "^14.11.8",
+    "chalk": "^3.0.0",
     "cpx": "^1.5.0",
+    "current-git-branch": "^1.1.0",
     "git-rev-sync": "^1.12.0",
-    "jest": "^23.6.0",
-    "jest-environment-jsdom": "^24.7.1",
+    "github-api": "^3.3.0",
+    "jest": "^27.1.0",
+    "jest-environment-jsdom": "^27.1.0",
     "live-server": "^1.2.1",
     "npm-run-all": "^4.1.5",
-    "prettier": "^1.19.1",
-    "rollup": "^1.6.0",
-    "rollup-plugin-typescript2": "^0.20.1",
+    "prettier": "^2.0.4",
+    "rollup": "^2.56.3",
+    "rollup-plugin-terser": "^7.0.2",
+    "rollup-plugin-typescript2": "^0.30.0",
     "sass": "^1.16.1",
     "source-map-support": "^0.5.10",
-    "ts-jest": "^23.10.5",
+    "ts-jest": "^27.0.5",
     "typescript": "^3.7.2",
     "uglify-es": "^3.3.9"
   },
   "jest": {
+    "testEnvironment": "jsdom",
     "roots": [
       "<rootDir>/src",
       "<rootDir>/tests"
@@ -68,6 +79,7 @@
     ]
   },
   "prettier": {
-    "printWidth": 100
+    "printWidth": 100,
+    "endOfLine": "auto"
   }
 }

roadmap.md

@@ -1,35 +1,22 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.0.0-beta2
-- Status: mostly stable
+- Current version: 1.4.9
+- Status: stable
 
 This roadmap is only an attempt at predicting Owl's future.  Everything may
 change!
 
 
-
-### December 2019
-
-If all goes well, Owl is upgraded to beta status. From now on, no API change,
-even small, is expected (but it still could happen).
-
-### End of 2019
-
-Release v1.0
-
-- API should be stable,
-- we will use semantic versioning,
-- we will maintain a changelog and an upgrade guide.
-
 ### 1.x
 
 - add chrome and firefox devtools,
-- add support for single file components,
 - fix every bugs,
 - improve documentation,
 - small backward compatible improvements.
 
-### 2.x (2021? 2022?)
+### 2.x (2020? 2021? 2022?)
+
+- stop support for `t-set` directive to define the content of a slot
 
 Maybe:
 

rollup.config.js

@@ -1,14 +1,70 @@
-import { version } from "./package.json";
+import pkg from "./package.json";
 import git from "git-rev-sync";
+import typescript from 'rollup-plugin-typescript2';
+import { terser } from "rollup-plugin-terser";
+
+const name = "owl";
+const extend = true;
+
+/**
+ * Meta data to be added on the __info__ object.
+ * Used to let external tools know the current owl version.
+ */
+const outro = `
+__info__.version = '${pkg.version}';
+__info__.date = '${new Date().toISOString()}';
+__info__.hash = '${git.short()}';
+__info__.url = 'https://github.com/odoo/owl';
+`;
+
+/**
+ * Generate from a string depicting a path a new path for the minified version.
+ * @param {string} pkgFileName file name
+ */
+function generateMinifiedNameFromPkgName(pkgFileName) {
+  const parts = pkgFileName.split('.');
+  parts.splice(parts.length - 1, 0, "min");
+  return parts.join('.');
+}
+
+/**
+ * Get the rollup config based on the arguments
+ * @param {string} format format of the bundle
+ * @param {string} generatedFileName generated file name
+ * @param {boolean} minified should it be minified
+ */
+function getConfigForFormat(format, generatedFileName, minified = false) {
+  return {
+    file: minified ? generateMinifiedNameFromPkgName(generatedFileName) : generatedFileName,
+    format: format,
+    name: name,
+    extend: extend,
+    outro: outro,
+    plugins: minified ? [terser()] : [],
+    indent: '    ', // indent with 4 spaces
+  };
+}
 
-// rollup.config.js
 export default {
-  input: "dist/owl/index.js",
-  output: {
-    file: "dist/owl.js",
-    format: "iife",
-    name: "owl",
-    extend: true,
-    outro: `exports.__info__.version = '${version}';\nexports.__info__.date = '${new Date().toISOString()}';\nexports.__info__.hash = '${git.short()}';\nexports.__info__.url = 'https://github.com/odoo/owl';`
-  }
+  input: "src/index.ts",
+  output: [
+
+    /**
+     * Read about module formats:
+     *  https://auth0.com/blog/javascript-module-systems-showdown/
+     *  https://medium.com/@kelin2025/so-you-wanna-use-es6-modules-714f48b3a953
+     */
+
+    getConfigForFormat('esm', pkg.module),
+    getConfigForFormat('esm', pkg.module, true),
+    getConfigForFormat('cjs', pkg.main),
+    getConfigForFormat('cjs', pkg.main, true),
+    getConfigForFormat('iife', pkg.browser),
+    getConfigForFormat('iife', pkg.browser, true),
+  ],
+  plugins: [
+    typescript({
+      useTsconfigDeclarationDir: true
+    }),
+  ]
 };

src/browser.ts

@@ -0,0 +1,30 @@
+export interface Browser {
+  setTimeout: Window["setTimeout"];
+  clearTimeout: Window["clearTimeout"];
+  setInterval: Window["setInterval"];
+  clearInterval: Window["clearInterval"];
+  requestAnimationFrame: Window["requestAnimationFrame"];
+  random: Math["random"];
+  Date: typeof Date;
+  fetch: Window["fetch"];
+  localStorage: Window["localStorage"];
+}
+
+let localStorage: Window["localStorage"] | null = null;
+
+export const browser: Browser = {
+  setTimeout: window.setTimeout.bind(window),
+  clearTimeout: window.clearTimeout.bind(window),
+  setInterval: window.setInterval.bind(window),
+  clearInterval: window.clearInterval.bind(window),
+  requestAnimationFrame: window.requestAnimationFrame.bind(window),
+  random: Math.random,
+  Date: window.Date,
+  fetch: (window.fetch || (() => {})).bind(window),
+  get localStorage() {
+    return localStorage || window.localStorage;
+  },
+  set localStorage(newLocalStorage: Window["localStorage"]) {
+    localStorage = newLocalStorage;
+  },
+};

src/component/component.ts

@@ -6,6 +6,8 @@ import "./directive";
 import { Fiber } from "./fiber";
 import "./props_validation";
 import { Scheduler, scheduler } from "./scheduler";
+import { activateSheet } from "./styles";
+import { Browser, browser } from "../browser";
 
 /**
  * Owl Component System
@@ -33,11 +35,22 @@ import { Scheduler, scheduler } from "./scheduler";
  */
 export interface Env {
   qweb: QWeb;
-  [key: string]: any;
+  browser: Browser;
 }
 
+export type MountPosition = "first-child" | "last-child" | "self";
+
 interface MountOptions {
-  position?: "first-child" | "last-child" | "self";
+  position?: MountPosition;
+}
+
+export const enum STATUS {
+  CREATED,
+  WILLSTARTED, // willstart has been called
+  RENDERED, // first render is completed (so, vnode is now defined)
+  MOUNTED, // is ready, and in DOM. It has a valid el
+  UNMOUNTED, // has a valid el, but is not in DOM
+  DESTROYED,
 }
 
 /**
@@ -45,20 +58,19 @@ interface MountOptions {
  * useful to typecheck and describe the internal keys used by Owl to manage the
  * component tree.
  */
-interface Internal<T extends Env, Props> {
+interface Internal<T extends Env> {
   // each component has a unique id, useful mostly to handle parent/child
   // relationships
   readonly id: number;
   depth: number;
   vnode: VNode | null;
   pvnode: VNode | null;
-  isMounted: boolean;
-  isDestroyed: boolean;
+  status: STATUS;
 
   // parent and children keys are obviously useful to setup the parent-children
   // relationship.
-  parent: Component<T, any> | null;
-  children: { [key: number]: Component<T, any> };
+  parent: Component<any, T> | null;
+  children: { [key: number]: Component<any, T> };
   // children mapping: from templateID to componentID. templateID identifies a
   // place in a template. The t-component directive needs it to be able to get
   // the component instance back whenever the template is rerendered.
@@ -84,7 +96,7 @@ interface Internal<T extends Env, Props> {
   willStartCB: Function | null;
   willUpdatePropsCB: Function | null;
   classObj: { [key: string]: boolean } | null;
-  refs: { [key: string]: Component<T, any> | HTMLElement | undefined } | null;
+  refs: { [key: string]: Component<any, T> | HTMLElement | undefined } | null;
 }
 
 export const portalSymbol = Symbol("portal"); // FIXME
@@ -94,18 +106,17 @@ export const portalSymbol = Symbol("portal"); // FIXME
 //------------------------------------------------------------------------------
 let nextId = 1;
 
-export class Component<T extends Env, Props extends {}> {
-  readonly __owl__: Internal<Env, Props>;
+export class Component<Props extends {} = any, T extends Env = Env> {
+  readonly __owl__: Internal<T>;
   static template?: string | null = null;
   static _template?: string | null = null;
-  static current: Component<any, any> | null = null;
+  static current: Component | null = null;
   static components = {};
   static props?: any;
   static defaultProps?: any;
   static env: any = {};
   // expose scheduler s.t. it can be mocked for testing purposes
   static scheduler: Scheduler = scheduler;
-  __target: HTMLElement | undefined;
 
   /**
    * The `el` is the root element of the component.  Note that it could be null:
@@ -129,7 +140,7 @@ export class Component<T extends Env, Props extends {}> {
    * hand.  Other components should be created automatically by the framework (with
    * the t-component directive in a template)
    */
-  constructor(parent?: Component<T, any> | null, props?: Props) {
+  constructor(parent?: Component<any, T> | null, props?: Props) {
     Component.current = this;
 
     let constr = this.constructor as any;
@@ -156,17 +167,23 @@ export class Component<T extends Env, Props extends {}> {
       if (!this.env.qweb) {
         this.env.qweb = new QWeb();
       }
+      // TODO: remove this in owl 2.0
+      if (!this.env.browser) {
+        this.env.browser = browser;
+      }
       this.env.qweb.on("update", this, () => {
-        if (this.__owl__.isMounted) {
-          this.render(true);
-        }
-        if (this.__owl__.isDestroyed) {
-          // this is unlikely to happen, but if a root widget is destroyed,
-          // we want to remove our subscription.  The usual way to do that
-          // would be to perform some check in the destroy method, but since
-          // it is very performance sensitive, and since this is a rare event,
-          // we simply do it lazily
-          this.env.qweb.off("update", this);
+        switch (this.__owl__.status) {
+          case STATUS.MOUNTED:
+            this.render(true);
+            break;
+          case STATUS.DESTROYED:
+            // this is unlikely to happen, but if a root widget is destroyed,
+            // we want to remove our subscription.  The usual way to do that
+            // would be to perform some check in the destroy method, but since
+            // it is very performance sensitive, and since this is a rare event,
+            // we simply do it lazily
+            this.env.qweb.off("update", this);
+            break;
         }
       });
       depth = 0;
@@ -179,8 +196,7 @@ export class Component<T extends Env, Props extends {}> {
       depth: depth,
       vnode: null,
       pvnode: null,
-      isMounted: false,
-      isDestroyed: false,
+      status: STATUS.CREATED,
       parent: parent || null,
       children: {},
       cmap: {},
@@ -197,10 +213,25 @@ export class Component<T extends Env, Props extends {}> {
       renderFn: qweb.render.bind(qweb, template),
       classObj: null,
       refs: null,
-      scope: null
+      scope: null,
     };
+    if (constr.style) {
+      this.__applyStyles(constr);
+    }
+    this.setup();
   }
 
+  /**
+   * setup is run just after the component is constructed. This is the standard
+   * location where the component can setup its hooks. It has some advantages
+   * over the constructor:
+   *  - it can be patched (useful in odoo ecosystem)
+   *  - it does not need to propagate the arguments to the super call
+   *
+   * Note: this method should not be called manually.
+   */
+  setup() {}
+
   /**
    * willStart is an asynchronous hook that can be implemented to perform some
    * action before the initial rendering of a component.
@@ -295,33 +326,49 @@ export class Component<T extends Env, Props extends {}> {
    * Note that a component can be mounted an unmounted several times
    */
   async mount(target: HTMLElement | DocumentFragment, options: MountOptions = {}): Promise<void> {
-    const position = options.position || "last-child";
-    const __owl__ = this.__owl__;
-    if (__owl__.isMounted) {
-      return Promise.resolve();
-    }
     if (!(target instanceof HTMLElement || target instanceof DocumentFragment)) {
       let message = `Component '${this.constructor.name}' cannot be mounted: the target is not a valid DOM node.`;
       message += `\nMaybe the DOM is not ready yet? (in that case, you can use owl.utils.whenReady)`;
       throw new Error(message);
     }
-    let inserter =
-      position === "last-child"
-        ? el => target.appendChild(el)
-        : position === "first-child"
-        ? el => target.prepend(el)
-        : el => {};
-    if (position === "self") {
-      this.__target = target as HTMLElement;
+    const position = options.position || "last-child";
+    const __owl__ = this.__owl__;
+    const currentFiber = __owl__.currentFiber;
+
+    switch (__owl__.status) {
+      case STATUS.CREATED: {
+        const fiber = new Fiber(null, this, true, target, position);
+        fiber.shouldPatch = false;
+        this.__prepareAndRender(fiber, () => {});
+        return scheduler.addFiber(fiber);
+      }
+      case STATUS.WILLSTARTED:
+      case STATUS.RENDERED:
+        currentFiber.target = target;
+        currentFiber.position = position;
+        return scheduler.addFiber(currentFiber);
+
+      case STATUS.UNMOUNTED: {
+        const fiber = new Fiber(null, this, true, target, position);
+        fiber.shouldPatch = false;
+        this.__render(fiber);
+        return scheduler.addFiber(fiber);
+      }
+
+      case STATUS.MOUNTED: {
+        if (position !== "self" && this.el!.parentNode !== target) {
+          const fiber = new Fiber(null, this, true, target, position);
+          fiber.shouldPatch = false;
+          this.__render(fiber);
+          return scheduler.addFiber(fiber);
+        } else {
+          return Promise.resolve();
+        }
+      }
+
+      case STATUS.DESTROYED:
+        throw new Error("Cannot mount a destroyed component");
     }
-    const fiber = new Fiber(null, this, false, inserter);
-    fiber.shouldPatch = false;
-    if (!__owl__.vnode) {
-      this.__prepareAndRender(fiber, () => {});
-    } else {
-      this.__render(fiber);
-    }
-    return scheduler.addFiber(fiber);
   }
 
   /**
@@ -329,7 +376,7 @@ export class Component<T extends Env, Props extends {}> {
    * to call willUnmount calls and remove the component from the DOM.
    */
   unmount() {
-    if (this.__owl__.isMounted) {
+    if (this.__owl__.status === STATUS.MOUNTED) {
       this.__callWillUnmount();
       this.el!.remove();
     }
@@ -346,24 +393,24 @@ export class Component<T extends Env, Props extends {}> {
    */
   async render(force: boolean = false): Promise<void> {
     const __owl__ = this.__owl__;
-    if (!__owl__.isMounted && !__owl__.currentFiber) {
-      // if we get here, this means that the component was either never mounted,
-      // or was unmounted and some state change  triggered a render. Either way,
-      // we do not want to actually render anything in this case.
+    const currentFiber = __owl__.currentFiber;
+    if (!__owl__.vnode && !currentFiber) {
       return;
     }
-    if (__owl__.currentFiber && !__owl__.currentFiber.isRendered) {
-      return scheduler.addFiber(__owl__.currentFiber.root);
+    if (currentFiber && !currentFiber.isRendered && !currentFiber.isCompleted) {
+      return scheduler.addFiber(currentFiber.root);
     }
+
     // if we aren't mounted at this point, it implies that there is a
     // currentFiber that is already rendered (isRendered is true), so we are
     // about to be mounted
-    const isMounted = __owl__.isMounted;
-    const fiber = new Fiber(null, this, force, null);
+    const status = __owl__.status;
+    const fiber = new Fiber(null, this, force, null, null);
     Promise.resolve().then(() => {
-      if (__owl__.isMounted || !isMounted) {
-        // we are mounted (__owl__.isMounted), or if we are currently being
-        // mounted (!isMounted), so we call __render
+      if (__owl__.status === STATUS.MOUNTED || status !== STATUS.MOUNTED) {
+        if (fiber.isCompleted || fiber.isRendered) {
+          return;
+        }
         this.__render(fiber);
       } else {
         // we were mounted when render was called, but we aren't anymore, so we
@@ -387,7 +434,7 @@ export class Component<T extends Env, Props extends {}> {
    */
   destroy() {
     const __owl__ = this.__owl__;
-    if (!__owl__.isDestroyed) {
+    if (__owl__.status !== STATUS.DESTROYED) {
       const el = this.el;
       this.__destroy(__owl__.parent);
       if (el) {
@@ -411,8 +458,8 @@ export class Component<T extends Env, Props extends {}> {
    * up to the parent DOM nodes. Thus, it must be called between mounted() and
    * willUnmount().
    */
-  trigger(eventType: string, payload?: any) {
-    this.__trigger(this, eventType, payload);
+  trigger<T = any>(eventType: string, payload?: T) {
+    this.__trigger<T>(this, eventType, payload);
   }
 
   //--------------------------------------------------------------------------
@@ -430,15 +477,14 @@ export class Component<T extends Env, Props extends {}> {
    * Note that it does not call the __callWillUnmount method to avoid visiting
    * all children many times.
    */
-  __destroy(parent: Component<any, any> | null) {
+  __destroy(parent: Component | null) {
     const __owl__ = this.__owl__;
-    const isMounted = __owl__.isMounted;
-    if (isMounted) {
+    if (__owl__.status === STATUS.MOUNTED) {
       if (__owl__.willUnmountCB) {
         __owl__.willUnmountCB();
       }
       this.willUnmount();
-      __owl__.isMounted = false;
+      __owl__.status = STATUS.UNMOUNTED;
     }
     const children = __owl__.children;
     for (let key in children) {
@@ -449,7 +495,7 @@ export class Component<T extends Env, Props extends {}> {
       delete parent.__owl__.children[id];
       __owl__.parent = null;
     }
-    __owl__.isDestroyed = true;
+    __owl__.status = STATUS.DESTROYED;
     delete __owl__.vnode;
     if (__owl__.currentFiber) {
       __owl__.currentFiber.isCompleted = true;
@@ -459,8 +505,7 @@ export class Component<T extends Env, Props extends {}> {
   __callMounted() {
     const __owl__ = this.__owl__;
 
-    __owl__.isMounted = true;
-    __owl__.currentFiber = null;
+    __owl__.status = STATUS.MOUNTED;
     this.mounted();
     if (__owl__.mountedCB) {
       __owl__.mountedCB();
@@ -473,15 +518,15 @@ export class Component<T extends Env, Props extends {}> {
       __owl__.willUnmountCB();
     }
     this.willUnmount();
-    __owl__.isMounted = false;
-    if (this.__owl__.currentFiber) {
-      this.__owl__.currentFiber.isCompleted = true;
-      this.__owl__.currentFiber.root.counter = 0;
+    __owl__.status = STATUS.UNMOUNTED;
+    if (__owl__.currentFiber) {
+      __owl__.currentFiber.isCompleted = true;
+      __owl__.currentFiber.root.counter = 0;
     }
     const children = __owl__.children;
     for (let id in children) {
       const comp = children[id];
-      if (comp.__owl__.isMounted) {
+      if (comp.__owl__.status === STATUS.MOUNTED) {
         comp.__callWillUnmount();
       }
     }
@@ -490,12 +535,12 @@ export class Component<T extends Env, Props extends {}> {
    * Private trigger method, allows to choose the component which triggered
    * the event in the first place
    */
-  __trigger(component: Component<any, any>, eventType: string, payload?: any) {
+  __trigger<T>(component: Component, eventType: string, payload?: T) {
     if (this.el) {
-      const ev = new OwlEvent(component, eventType, {
+      const ev = new OwlEvent<T>(component, eventType, {
         bubbles: true,
         cancelable: true,
-        detail: payload
+        detail: payload,
       });
       const triggerHook = this.env[portalSymbol as any];
       if (triggerHook) {
@@ -513,7 +558,7 @@ export class Component<T extends Env, Props extends {}> {
     const shouldUpdate = parentFiber.force || this.shouldUpdate(nextProps);
     if (shouldUpdate) {
       const __owl__ = this.__owl__;
-      const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
+      const fiber = new Fiber(parentFiber, this, parentFiber.force, null, null);
       if (!parentFiber.child) {
         parentFiber.child = fiber;
       } else {
@@ -530,7 +575,7 @@ export class Component<T extends Env, Props extends {}> {
       }
       await Promise.all([
         this.willUpdateProps(nextProps),
-        __owl__.willUpdatePropsCB && __owl__.willUpdatePropsCB(nextProps)
+        __owl__.willUpdatePropsCB && __owl__.willUpdatePropsCB(nextProps),
       ]);
       if (fiber.isCompleted) {
         return;
@@ -545,20 +590,8 @@ export class Component<T extends Env, Props extends {}> {
    * Main patching method. We call the virtual dom patch method here to convert
    * a virtual dom vnode into some actual dom.
    */
-  __patch(vnode: VNode) {
-    const __owl__ = this.__owl__;
-    if (this.__target) {
-      if (this.__target.tagName.toLowerCase() !== vnode.sel) {
-        throw new Error(
-          `Cannot attach '${this.constructor.name}' to target node (not same tag name)`
-        );
-      }
-      __owl__.vnode = patch(this.__target, vnode);
-      delete this.__target;
-    } else {
-      const target = __owl__.vnode || document.createElement(vnode.sel!);
-      __owl__.vnode = patch(target, vnode);
-    }
+  __patch(target: HTMLElement | VNode | DocumentFragment, vnode: VNode) {
+    this.__owl__.vnode = patch(target as any, vnode);
   }
 
   /**
@@ -568,7 +601,7 @@ export class Component<T extends Env, Props extends {}> {
    */
   __prepare(parentFiber: Fiber, scope: any, cb: CallableFunction): Fiber {
     this.__owl__.scope = scope;
-    const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
+    const fiber = new Fiber(parentFiber, this, parentFiber.force, null, null);
     fiber.shouldPatch = false;
     if (!parentFiber.child) {
       parentFiber.child = fiber;
@@ -580,6 +613,20 @@ export class Component<T extends Env, Props extends {}> {
     return fiber;
   }
 
+  /**
+   * Apply the stylesheets defined by the component. Note that we need to make
+   * sure all inherited stylesheets are applied as well.  We then delete the
+   * `style` key from the constructor to make sure we do not apply it again.
+   */
+  private __applyStyles(constr) {
+    while (constr && constr.style) {
+      if (constr.hasOwnProperty("style")) {
+        activateSheet(constr.style, constr.name);
+        delete constr.style;
+      }
+      constr = constr.__proto__;
+    }
+  }
   __getTemplate(qweb: QWeb): string {
     let p = (<any>this).constructor;
     if (!p.hasOwnProperty("_template")) {
@@ -587,9 +634,10 @@ export class Component<T extends Env, Props extends {}> {
       // key. So we fall back on looking for a template matching its name (or
       // one of its subclass).
 
-      let template: string;
-      while ((template = p.name) && !(template in qweb.templates) && p !== Component) {
+      let template: string = p.name;
+      while (!(template in qweb.templates) && p !== Component) {
         p = p.__proto__;
+        template = p.name;
       }
       if (p === Component) {
         throw new Error(`Could not find template for component "${this.constructor.name}"`);
@@ -599,18 +647,25 @@ export class Component<T extends Env, Props extends {}> {
     }
     return p._template;
   }
+
   async __prepareAndRender(fiber: Fiber, cb: CallableFunction) {
     try {
-      await Promise.all([this.willStart(), this.__owl__.willStartCB && this.__owl__.willStartCB()]);
+      const proms = Promise.all([
+        this.willStart(),
+        this.__owl__.willStartCB && this.__owl__.willStartCB(),
+      ]);
+      this.__owl__.status = STATUS.WILLSTARTED;
+      await proms;
+      if (this.__owl__.status === <any>STATUS.DESTROYED) {
+        return Promise.resolve();
+      }
     } catch (e) {
       fiber.handleError(e);
       return Promise.resolve();
     }
-    if (this.__owl__.isDestroyed) {
-      return Promise.resolve();
-    }
     if (!fiber.isCompleted) {
       this.__render(fiber);
+      this.__owl__.status = STATUS.RENDERED;
       cb();
     }
   }
@@ -624,16 +679,35 @@ export class Component<T extends Env, Props extends {}> {
     try {
       let vnode = __owl__.renderFn!(this, {
         handlers: __owl__.boundHandlers,
-        fiber: fiber
+        fiber: fiber,
       });
       // we iterate over the children to detect those that no longer belong to the
       // current rendering: those ones, if not mounted yet, can (and have to) be
       // destroyed right now, because they are not in the DOM, and thus we won't
       // be notified later on (when patching), that they are removed from the DOM
       for (let childKey in __owl__.children) {
-        let child = __owl__.children[childKey];
-        if (!child.__owl__.isMounted && child.__owl__.parentLastFiberId < fiber.id) {
-          child.destroy();
+        const child = __owl__.children[childKey];
+        const childOwl = child.__owl__;
+        if (childOwl.status !== STATUS.MOUNTED && childOwl.parentLastFiberId < fiber.id) {
+          // we only do here a "soft" destroy, meaning that we leave the child
+          // dom node alone, without removing it.  Most of the time, it does not
+          // matter, because the child component is already unmounted.  However,
+          // if some of its parent have been unmounted, the child could actually
+          // still be attached to its parent, and this may be important if we
+          // want to remount the parent, because the vdom need to match the
+          // actual DOM
+          child.__destroy(childOwl.parent);
+          if (childOwl.pvnode) {
+            // we remove the key here to make sure that the patching algorithm
+            // is able to make the difference between this pvnode and an eventual
+            // other instance of the same component
+            delete childOwl.pvnode.key;
+            // Since the component has been unmounted, we do not want to actually
+            // call a remove hook.  This is pretty important, since the t-component
+            // directive actually disabled it, so the vdom algorithm will just
+            // not remove the child elm if we don't remove the hook.
+            delete childOwl.pvnode.data!.hook!.remove;
+          }
         }
       }
       if (!vnode) {
@@ -661,17 +735,6 @@ export class Component<T extends Env, Props extends {}> {
     }
   }
 
-  /**
-   * Only called by qweb t-component directive (when t-keepalive is set)
-   */
-  __remount() {
-    const __owl__ = this.__owl__;
-    if (!__owl__.isMounted) {
-      __owl__.isMounted = true;
-      this.mounted();
-    }
-  }
-
   /**
    * Apply default props (only top level).
    *
@@ -685,3 +748,34 @@ export class Component<T extends Env, Props extends {}> {
     }
   }
 }
+
+interface MountParameters {
+  env?: Env;
+  target: HTMLElement | DocumentFragment;
+  props?: any;
+  position?: MountOptions["position"];
+}
+
+interface Type<T> extends Function {
+  new (...args: any[]): T;
+}
+
+export async function mount<T extends Type<Component>>(
+  C: T,
+  params: MountParameters
+): Promise<InstanceType<T>> {
+  const { env, props, target } = params;
+  let origEnv = C.hasOwnProperty("env") ? (C as any).env : null;
+  if (env) {
+    (C as any as typeof Component).env = env;
+  }
+  const component: Component = new C(null, props);
+  if (origEnv) {
+    (C as any).env = origEnv;
+  } else {
+    delete (C as any).env;
+  }
+  const position = params.position || "last-child";
+  await component.mount(target, { position });
+  return component as any;
+}

src/component/directive.ts

@@ -1,13 +1,14 @@
 import { QWeb } from "../qweb/index";
 import { INTERP_REGEXP } from "../qweb/compilation_context";
 import { makeHandlerCode, MODS_CODE } from "../qweb/extensions";
+import { STATUS } from "./component";
 
 //------------------------------------------------------------------------------
 // t-component
 //------------------------------------------------------------------------------
 
 const T_COMPONENT_MODS_CODE = Object.assign({}, MODS_CODE, {
-  self: "if (e.target !== vn.elm) {return}"
+  self: "if (e.target !== vn.elm) {return}",
 });
 
 QWeb.utils.defineProxy = function defineProxy(target, source) {
@@ -18,11 +19,31 @@ QWeb.utils.defineProxy = function defineProxy(target, source) {
       },
       set(val) {
         source[k] = val;
-      }
+      },
     });
   }
 };
 
+QWeb.utils.assignHooks = function assignHooks(dataObj, hooks) {
+  if ("hook" in dataObj) {
+    const hookObject = dataObj.hook;
+    for (let name in hooks) {
+      const current = hookObject[name];
+      const fn = hooks[name];
+      if (current) {
+        hookObject[name] = (...args) => {
+          current(...args);
+          fn(...args);
+        };
+      } else {
+        hookObject[name] = fn;
+      }
+    }
+  } else {
+    dataObj.hook = hooks;
+  }
+};
+
 /**
  * The t-component directive is certainly a complicated and hard to maintain piece
  * of code.  To help you, fellow developer, if you have to maintain it, I offer
@@ -207,22 +228,39 @@ QWeb.addDirective({
       if (name.startsWith("t-on-")) {
         events.push([name, value]);
       } else if (name === "t-transition") {
-        transition = value;
+        if (QWeb.enableTransitions) {
+          transition = value;
+        }
       } else if (!name.startsWith("t-")) {
         if (name !== "class" && name !== "style") {
           // this is a prop!
-          props[name] = ctx.formatExpression(value);
+          if (value.includes("=>")) {
+            props[name] = ctx.captureExpression(value);
+          } else {
+            props[name] = ctx.formatExpression(value) || "undefined";
+          }
         }
       }
     }
 
     // computing the props string representing the props object
     let propStr = Object.keys(props)
-      .map(k => k + ":" + props[k])
+      .map((k) => k + ":" + props[k])
       .join(",");
     let componentID = ctx.generateID();
 
-    const templateKey = ctx.generateTemplateKey();
+    let hasDefinedKey = false;
+    let templateKey;
+    if (node.tagName === "t" && !node.hasAttribute("t-key") && value.match(INTERP_REGEXP)) {
+      defineComponentKey();
+      const id = ctx.generateID();
+      // the ___ is to make sure we have no possible conflict with normal
+      // template keys
+      ctx.addLine(`let k${id} = '___' + componentKey${componentID}`);
+      templateKey = `k${id}`;
+    } else {
+      templateKey = ctx.generateTemplateKey();
+    }
     let ref = node.getAttribute("t-ref");
     let refExpr = "";
     let refKey: string = "";
@@ -260,7 +298,7 @@ QWeb.addDirective({
         let classDef = classAttr
           .trim()
           .split(/\s+/)
-          .map(a => `'${a}':true`)
+          .map((a) => `'${a}':true`)
           .join(",");
         classObj = `_${ctx.generateID()}`;
         ctx.addLine(`let ${classObj} = {${classDef}};`);
@@ -268,7 +306,7 @@ QWeb.addDirective({
       if (tattClass) {
         let tattExpr = ctx.formatExpression(tattClass);
         if (tattExpr[0] !== "{" || tattExpr[tattExpr.length - 1] !== "}") {
-          tattExpr = `utils.toObj(${tattExpr})`;
+          tattExpr = `utils.toClassObj(${tattExpr})`;
         }
         if (classAttr) {
           ctx.addLine(`Object.assign(${classObj}, ${tattExpr})`);
@@ -278,7 +316,9 @@ QWeb.addDirective({
         }
       }
       let eventsCode = events
-        .map(function([name, value]) {
+        .map(function ([name, value]) {
+          const capture = name.match(/\.capture/);
+          name = capture ? name.replace(/\.capture/, "") : name;
           const { event, handler } = makeHandlerCode(
             ctx,
             name,
@@ -286,12 +326,15 @@ QWeb.addDirective({
             false,
             T_COMPONENT_MODS_CODE
           );
+          if (capture) {
+            return `vn.elm.addEventListener('${event}', ${handler}, true);`;
+          }
           return `vn.elm.addEventListener('${event}', ${handler});`;
         })
         .join("");
       const styleExpr = tattStyle || (styleAttr ? `'${styleAttr}'` : false);
       const styleCode = styleExpr ? `vn.elm.style = ${styleExpr};` : "";
-      createHook = `vnode.data.hook = {create(_, vn){${styleCode}${eventsCode}}};`;
+      createHook = `utils.assignHooks(vnode.data, {create(_, vn){${styleCode}${eventsCode}}});`;
     }
 
     ctx.addLine(
@@ -308,7 +351,7 @@ QWeb.addDirective({
     }
     if (hasDynamicProps) {
       const dynamicProp = ctx.formatExpression(node.getAttribute("t-props")!);
-      ctx.addLine(`let props${componentID} = Object.assign({${propStr}}, ${dynamicProp});`);
+      ctx.addLine(`let props${componentID} = Object.assign({}, ${dynamicProp}, {${propStr}});`);
     } else {
       ctx.addLine(`let props${componentID} = {${propStr}};`);
     }
@@ -327,14 +370,14 @@ QWeb.addDirective({
     // SLOTS
     const hasSlots = node.childNodes.length;
 
-    let scope = hasSlots ? `Object.assign(Object.create(context), scope)` : "undefined";
+    let scope = hasSlots ? `utils.combine(context, scope)` : "undefined";
 
     ctx.addIf(`w${componentID}`);
 
     // need to update component
     let styleCode = "";
     if (tattStyle) {
-      styleCode = `.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};w${componentID}.el.style=${tattStyle};});`;
+      styleCode = `.then(()=>{if (w${componentID}.__owl__.status === ${STATUS.DESTROYED}) {return};w${componentID}.el.style=${tattStyle};});`;
     }
     ctx.addLine(
       `w${componentID}.__updateProps(props${componentID}, extra.fiber, ${scope})${styleCode};`
@@ -350,14 +393,17 @@ QWeb.addDirective({
     ctx.addElse();
 
     // new component
-    let dynamicFallback = "";
-    if (!value.match(INTERP_REGEXP)) {
-      dynamicFallback = `|| ${ctx.formatExpression(value)}`;
+    function defineComponentKey() {
+      if (!hasDefinedKey) {
+        const interpValue = ctx.interpolate(value);
+        ctx.addLine(`let componentKey${componentID} = ${interpValue};`);
+        hasDefinedKey = true;
+      }
     }
-    const interpValue = ctx.interpolate(value);
-    ctx.addLine(`let componentKey${componentID} = ${interpValue};`);
+    defineComponentKey();
+    const contextualValue = value.match(INTERP_REGEXP) ? "false" : ctx.formatExpression(value);
     ctx.addLine(
-      `let W${componentID} = context.constructor.components[componentKey${componentID}] || QWeb.components[componentKey${componentID}]${dynamicFallback};`
+      `let W${componentID} = ${contextualValue} || context.constructor.components[componentKey${componentID}] || QWeb.components[componentKey${componentID}];`
     );
 
     // maybe only do this in dev mode...
@@ -368,33 +414,76 @@ QWeb.addDirective({
     if (transition) {
       ctx.addLine(`const __patch${componentID} = w${componentID}.__patch;`);
       ctx.addLine(
-        `w${componentID}.__patch = fiber => {__patch${componentID}.call(w${componentID}, fiber); if(!w${componentID}.__owl__.transitionInserted){w${componentID}.__owl__.transitionInserted = true;utils.transitionInsert(w${componentID}.__owl__.vnode, '${transition}');}};`
+        `w${componentID}.__patch = (t, vn) => {__patch${componentID}.call(w${componentID}, t, vn); if(!w${componentID}.__owl__.transitionInserted){w${componentID}.__owl__.transitionInserted = true;utils.transitionInsert(w${componentID}.__owl__.vnode, '${transition}');}};`
       );
     }
     ctx.addLine(`parent.__owl__.cmap[${templateKey}] = w${componentID}.__owl__.id;`);
 
     if (hasSlots) {
       const clone = <Element>node.cloneNode(true);
-      const slotNodes = clone.querySelectorAll("[t-set]");
+
+      // The next code is a fallback for compatibility reason. It accepts t-set
+      // elements that are direct children with a non empty body as nodes defining
+      // the content of a slot.
+      //
+      // This is wrong, but is necessary to prevent breaking all existing Owl
+      // code using slots. This will be removed in v2.0 someday. Meanwhile,
+      // please use t-set-slot everywhere you need to set the content of a
+      // slot.
+      for (let node of clone.children) {
+        if (node.hasAttribute("t-set") && node.hasChildNodes()) {
+          node.setAttribute("t-set-slot", node.getAttribute("t-set")!);
+          node.removeAttribute("t-set");
+        }
+      }
+      const slotNodes = Array.from(clone.querySelectorAll("[t-set-slot]"));
+      const slotNames = new Set<string>();
       const slotId = QWeb.nextSlotId++;
       ctx.addLine(`w${componentID}.__owl__.slotId = ${slotId};`);
       if (slotNodes.length) {
         for (let i = 0, length = slotNodes.length; i < length; i++) {
           const slotNode = slotNodes[i];
+          // check if this is defined in a sub component (in which case it should
+          // be ignored)
+          let el = slotNode.parentElement;
+          let isInSubComponent = false;
+          while (el !== clone) {
+            if (
+              el!.hasAttribute("t-component") ||
+              el!.tagName[0] === el!.tagName[0].toUpperCase()
+            ) {
+              isInSubComponent = true;
+              break;
+            }
+            el = el.parentElement;
+          }
+          if (isInSubComponent) {
+            continue;
+          }
+          let key = slotNode.getAttribute("t-set-slot")!;
+          if (slotNames.has(key)) {
+            continue;
+          }
+          slotNames.add(key);
+          slotNode.removeAttribute("t-set-slot");
           slotNode.parentElement!.removeChild(slotNode);
-          const key = slotNode.getAttribute("t-set")!;
-          slotNode.removeAttribute("t-set");
-          const slotFn = qweb._compile(`slot_${key}_template`, slotNode, ctx);
+
+          const slotFn = qweb._compile(`slot_${key}_template`, { elem: slotNode, hasParent: true });
           QWeb.slots[`${slotId}_${key}`] = slotFn;
         }
       }
       if (clone.childNodes.length) {
+        let hasContent = false;
         const t = clone.ownerDocument!.createElement("t");
         for (let child of Object.values(clone.childNodes)) {
+          hasContent =
+            hasContent || (child instanceof Text ? Boolean(child.textContent.trim().length) : true);
           t.appendChild(child);
         }
-        const slotFn = qweb._compile(`slot_default_template`, t, ctx);
-        QWeb.slots[`${slotId}_default`] = slotFn;
+        if (hasContent) {
+          const slotFn = qweb._compile(`slot_default_template`, { elem: t, hasParent: true });
+          QWeb.slots[`${slotId}_default`] = slotFn;
+        }
       }
     }
 
@@ -423,5 +512,5 @@ QWeb.addDirective({
     ctx.addLine(`w${componentID}.__owl__.parentLastFiberId = extra.fiber.id;`);
 
     return true;
-  }
+  },
 });

src/component/fiber.ts

@@ -1,5 +1,5 @@
 import { h, VNode } from "../vdom/index";
-import { Component } from "./component";
+import { Component, MountPosition, STATUS } from "./component";
 import { scheduler } from "./scheduler";
 
 /**
@@ -46,11 +46,12 @@ export class Fiber {
   // scheduler.
   counter: number = 0;
 
-  inserter: (el: HTMLElement) => void | null;
+  target: HTMLElement | DocumentFragment | null;
+  position: MountPosition | null;
 
   scope: any;
 
-  component: Component<any, any>;
+  component: Component;
   vnode: VNode | null = null;
 
   root: Fiber;
@@ -61,10 +62,17 @@ export class Fiber {
 
   error?: Error;
 
-  constructor(parent: Fiber | null, component: Component<any, any>, force, inserter) {
+  constructor(
+    parent: Fiber | null,
+    component: Component,
+    force: boolean,
+    target: HTMLElement | DocumentFragment | null,
+    position: MountPosition | null
+  ) {
     this.component = component;
     this.force = force;
-    this.inserter = inserter;
+    this.target = target;
+    this.position = position;
 
     const __owl__ = component.__owl__;
     this.scope = __owl__.scope;
@@ -74,6 +82,7 @@ export class Fiber {
 
     let oldFiber = __owl__.currentFiber;
     if (oldFiber && !oldFiber.isCompleted) {
+      this.force = true;
       if (oldFiber.root === oldFiber && !parent) {
         // both oldFiber and this fiber are root fibers
         this._reuseFiber(oldFiber);
@@ -98,6 +107,8 @@ export class Fiber {
    */
   _reuseFiber(oldFiber: Fiber) {
     oldFiber.cancel(); // cancel children fibers
+    oldFiber.target = this.target || oldFiber.target;
+    oldFiber.position = this.position || oldFiber.position;
     oldFiber.isCompleted = false; // keep the root fiber alive
     oldFiber.isRendered = false; // the fiber has to be re-rendered
     if (oldFiber.child) {
@@ -179,13 +190,15 @@ export class Fiber {
   complete() {
     let component = this.component;
     this.isCompleted = true;
-    if (!this.inserter && !component.__owl__.isMounted) {
+    const status = component.__owl__.status;
+    if (status === STATUS.DESTROYED) {
       return;
     }
 
     // build patchQueue
     const patchQueue: Fiber[] = [];
-    const doWork: (Fiber) => Fiber | null = function(f) {
+    const doWork: (Fiber) => Fiber | null = function (f) {
+      f.component.__owl__.currentFiber = null;
       patchQueue.push(f);
       return f.child;
     };
@@ -193,14 +206,16 @@ export class Fiber {
     const patchLen = patchQueue.length;
 
     // call willPatch hook on each fiber of patchQueue
-    for (let i = 0; i < patchLen; i++) {
-      const fiber = patchQueue[i];
-      if (fiber.shouldPatch) {
-        component = fiber.component;
-        if (component.__owl__.willPatchCB) {
-          component.__owl__.willPatchCB();
+    if (status === STATUS.MOUNTED) {
+      for (let i = 0; i < patchLen; i++) {
+        const fiber = patchQueue[i];
+        if (fiber.shouldPatch) {
+          component = fiber.component;
+          if (component.__owl__.willPatchCB) {
+            component.__owl__.willPatchCB();
+          }
+          component.willPatch();
         }
-        component.willPatch();
       }
     }
 
@@ -208,32 +223,76 @@ export class Fiber {
     for (let i = patchLen - 1; i >= 0; i--) {
       const fiber = patchQueue[i];
       component = fiber.component;
-      component.__patch(fiber.vnode!);
-      if (!fiber.shouldPatch && (!fiber.inserter || i !== 0)) {
-        component.__owl__.pvnode!.elm = component.__owl__.vnode!.elm;
+      if (fiber.target && i === 0) {
+        let target;
+        if (fiber.position === "self") {
+          target = fiber.target;
+          if ((target as HTMLElement).tagName.toLowerCase() !== fiber.vnode!.sel) {
+            throw new Error(
+              `Cannot attach '${component.constructor.name}' to target node (not same tag name)`
+            );
+          }
+          // In self mode, we *know* we are to take possession of the target
+          // Hence we manually create the corresponding VNode and copy the "key" in data
+          const selfVnodeData = fiber.vnode!.data ? { key: fiber.vnode!.data.key } : {};
+          const selfVnode = h(fiber.vnode!.sel, selfVnodeData);
+          selfVnode.elm = target;
+          target = selfVnode;
+        } else {
+          target = component.__owl__.vnode || document.createElement(fiber.vnode!.sel!);
+        }
+        component.__patch(target!, fiber.vnode!);
+      } else {
+        const vnode = component.__owl__.vnode;
+        if (fiber.shouldPatch && vnode) {
+          component.__patch(vnode, fiber.vnode!);
+          // When updating a Component's props (in directive),
+          // the component has a pvnode AND should be patched.
+          // However, its pvnode.elm may have changed if it is a High Order Component
+          if (component.__owl__.pvnode) {
+            component.__owl__.pvnode.elm = component.__owl__.vnode!.elm;
+          }
+        } else {
+          component.__patch(document.createElement(fiber.vnode!.sel!), fiber.vnode!);
+          component.__owl__.pvnode!.elm = component.__owl__.vnode!.elm;
+        }
       }
-      component.__owl__.currentFiber = null;
     }
 
     // insert into the DOM (mount case)
     let inDOM = false;
-    if (this.inserter) {
-      this.inserter(this.component.el!);
+    if (this.target) {
+      switch (this.position) {
+        case "first-child":
+          this.target.prepend(this.component.el!);
+          break;
+        case "last-child":
+          this.target.appendChild(this.component.el!);
+          break;
+      }
       inDOM = document.body.contains(this.component.el);
       this.component.env.qweb.trigger("dom-appended");
     }
 
     // call patched/mounted hook on each fiber of (reversed) patchQueue
-    for (let i = patchLen - 1; i >= 0; i--) {
-      const fiber = patchQueue[i];
-      component = fiber.component;
-      if (fiber.shouldPatch && !this.inserter) {
-        component.patched();
-        if (component.__owl__.patchedCB) {
-          component.__owl__.patchedCB();
+    if (status === STATUS.MOUNTED || inDOM) {
+      for (let i = patchLen - 1; i >= 0; i--) {
+        const fiber = patchQueue[i];
+        component = fiber.component;
+        if (fiber.shouldPatch && !this.target) {
+          component.patched();
+          if (component.__owl__.patchedCB) {
+            component.__owl__.patchedCB();
+          }
+        } else {
+          component.__callMounted();
         }
-      } else if (this.inserter ? inDOM : true) {
-        component.__callMounted();
+      }
+    } else {
+      for (let i = patchLen - 1; i >= 0; i--) {
+        const fiber = patchQueue[i];
+        component = fiber.component;
+        component.__owl__.status = STATUS.UNMOUNTED;
       }
     }
   }
@@ -242,7 +301,7 @@ export class Fiber {
    * Cancel a fiber and all its children.
    */
   cancel() {
-    this._walk(f => {
+    this._walk((f) => {
       if (!f.isRendered) {
         f.root.counter--;
       }
@@ -265,22 +324,43 @@ export class Fiber {
 
     const qweb = component.env.qweb;
     let root = component;
-    let canCatch = false;
-    while (component && !(canCatch = !!component.catchError)) {
-      root = component;
-      component = component.__owl__.parent!;
-    }
-    qweb.trigger("error", error);
 
-    if (canCatch) {
-      component.catchError!(error);
-    } else {
+    function handle(error) {
+      let canCatch = false;
+      qweb.trigger("error", error);
+      while (component && !(canCatch = !!component.catchError)) {
+        root = component;
+        component = component.__owl__.parent!;
+      }
+      if (canCatch) {
+        try {
+          component.catchError!(error);
+        } catch (e) {
+          root = component;
+          component = component.__owl__.parent!;
+          return handle(e);
+        }
+        return true;
+      }
+      return false;
+    }
+
+    let isHandled = handle(error);
+
+    if (!isHandled) {
       // the 3 next lines aim to mark the root fiber as being in error, and
       // to force it to end, without waiting for its children
       this.root.counter = 0;
       this.root.error = error;
       scheduler.flush();
-      root.destroy();
+      // at this point, the state of the application is corrupted and we could
+      // have a lot of issues or crashes. So we destroy the application in a try
+      // catch and swallow these errors because the fiber is already in error,
+      // and this is the actual issue that needs to be solved, not those followup
+      // errors.
+      try {
+        root.destroy();
+      } catch (e) {}
     }
   }
 }

src/component/props_validation.ts

@@ -11,7 +11,7 @@ import { QWeb } from "../qweb/index";
  * This is why it is only done in 'dev' mode.
  */
 
-QWeb.utils.validateProps = function(Widget, props: Object) {
+QWeb.utils.validateProps = function (Widget, props: Object) {
   const propsDef = (<any>Widget).props;
   if (propsDef instanceof Array) {
     // list of strings (prop names)
@@ -37,7 +37,7 @@ QWeb.utils.validateProps = function(Widget, props: Object) {
         if (propsDef[propName] && !propsDef[propName].optional) {
           throw new Error(`Missing props '${propName}' (component '${Widget.name}')`);
         } else {
-          break;
+          continue;
         }
       }
       let isValid;

src/component/scheduler.ts

@@ -1,4 +1,5 @@
 import { Fiber } from "./fiber";
+import { browser } from "../browser";
 
 /**
  * Owl Scheduler Class
@@ -19,9 +20,9 @@ interface Task {
 export class Scheduler {
   tasks: Task[] = [];
   isRunning: boolean = false;
-  requestAnimationFrame: typeof window.requestAnimationFrame;
+  requestAnimationFrame: Window["requestAnimationFrame"];
 
-  constructor(requestAnimationFrame) {
+  constructor(requestAnimationFrame: Window["requestAnimationFrame"]) {
     this.requestAnimationFrame = requestAnimationFrame;
   }
 
@@ -34,7 +35,7 @@ export class Scheduler {
     this.isRunning = false;
   }
 
-  addFiber(fiber): Promise<void> {
+  addFiber(fiber: Fiber): Promise<void> {
     // if the fiber was remapped into a larger rendering fiber, it may not be a
     // root fiber.  But we only want to register root fibers
     fiber = fiber.root;
@@ -49,7 +50,7 @@ export class Scheduler {
             return reject(fiber.error);
           }
           resolve();
-        }
+        },
       });
       if (!this.isRunning) {
         this.start();
@@ -57,6 +58,17 @@ export class Scheduler {
     });
   }
 
+  rejectFiber(fiber: Fiber, reason: string) {
+    fiber = fiber.root;
+    const index = this.tasks.findIndex((t) => t.fiber === fiber);
+    if (index >= 0) {
+      const [task] = this.tasks.splice(index, 1);
+      fiber.cancel();
+      fiber.error = new Error(reason);
+      task.callback();
+    }
+  }
+
   /**
    * Process all current tasks. This only applies to the fibers that are ready.
    * Other tasks are left unchanged.
@@ -64,7 +76,7 @@ export class Scheduler {
   flush() {
     let tasks = this.tasks;
     this.tasks = [];
-    tasks = tasks.filter(task => {
+    tasks = tasks.filter((task) => {
       if (task.fiber.isCompleted) {
         task.callback();
         return false;
@@ -98,5 +110,4 @@ export class Scheduler {
   }
 }
 
-const raf = window.requestAnimationFrame.bind(window);
-export const scheduler = new Scheduler(raf);
+export const scheduler = new Scheduler(browser.requestAnimationFrame);

src/component/styles.ts

@@ -0,0 +1,70 @@
+/**
+ * Owl Style System
+ *
+ * This files contains the Owl code related to processing (extended) css strings
+ * and creating/adding <style> tags to the document head.
+ */
+
+export const STYLESHEETS: { [id: string]: HTMLStyleElement } = {};
+
+export function processSheet(str: string): string {
+  const tokens = str.split(/(\{|\}|;)/).map((s) => s.trim());
+  const selectorStack: string[][] = [];
+  const parts: string[] = [];
+  let rules: string[] = [];
+  function generateSelector(stackIndex: number, parentSelector?: string) {
+    const parts: string[] = [];
+    for (const selector of selectorStack[stackIndex]) {
+      let part = (parentSelector && parentSelector + " " + selector) || selector;
+      if (part.includes("&")) {
+        part = selector.replace(/&/g, parentSelector || "");
+      }
+      if (stackIndex < selectorStack.length - 1) {
+        part = generateSelector(stackIndex + 1, part);
+      }
+      parts.push(part);
+    }
+    return parts.join(", ");
+  }
+  function generateRules() {
+    if (rules.length) {
+      parts.push(generateSelector(0) + " {");
+      parts.push(...rules);
+      parts.push("}");
+      rules = [];
+    }
+  }
+  while (tokens.length) {
+    let token = tokens.shift()!;
+    if (token === "}") {
+      generateRules();
+      selectorStack.pop();
+    } else {
+      if (tokens[0] === "{") {
+        generateRules();
+        selectorStack.push(token.split(/\s*,\s*/));
+        tokens.shift();
+      }
+      if (tokens[0] === ";") {
+        rules.push("  " + token + ";");
+      }
+    }
+  }
+  return parts.join("\n");
+}
+export function registerSheet(id: string, css: string) {
+  const sheet = document.createElement("style");
+  sheet.innerHTML = processSheet(css);
+  STYLESHEETS[id] = sheet;
+}
+
+export function activateSheet(id, name) {
+  const sheet = STYLESHEETS[id];
+  if (!sheet) {
+    throw new Error(
+      `Invalid css stylesheet for component '${name}'. Did you forget to use the 'css' tag helper?`
+    );
+  }
+  sheet.setAttribute("component", name);
+  document.head.appendChild(sheet);
+}

src/config.ts

@@ -1,4 +1,5 @@
 import { QWeb } from "./qweb/index";
+import { TRANSLATABLE_ATTRS } from "./qweb/qweb";
 
 /**
  * This file creates and exports the OWL 'config' object, with keys:
@@ -8,9 +9,13 @@ import { QWeb } from "./qweb/index";
 
 interface Config {
   mode: string;
+  enableTransitions: boolean;
+  translatableAttributes: string[];
 }
 
-export const config = {} as Config;
+export const config = {
+  translatableAttributes: TRANSLATABLE_ATTRS,
+} as Config;
 
 Object.defineProperty(config, "mode", {
   get() {
@@ -19,12 +24,19 @@ Object.defineProperty(config, "mode", {
   set(mode: string) {
     QWeb.dev = mode === "dev";
     if (QWeb.dev) {
-      const url = `https://github.com/odoo/owl/blob/master/doc/reference/config.md#mode`;
-      console.warn(
-        `Owl is running in 'dev' mode.  This is not suitable for production use. See ${url} for more information.`
-      );
-    } else {
-      console.log(`Owl is now running in 'prod' mode.`);
+      console.info(`Owl is running in 'dev' mode.
+
+This is not suitable for production use.
+See https://github.com/odoo/owl/blob/master/doc/reference/config.md#mode for more information.`);
     }
-  }
+  },
+});
+
+Object.defineProperty(config, "enableTransitions", {
+  get() {
+    return QWeb.enableTransitions;
+  },
+  set(value: boolean) {
+    QWeb.enableTransitions = value;
+  },
 });

src/context.ts

@@ -79,9 +79,9 @@ export class Context extends EventBus {
   async __notifyComponents() {
     const rev = ++this.rev;
     const subscriptions = this.subscriptions.update;
-    const groups = partitionBy(subscriptions, s => (s.owner ? s.owner.__owl__.depth : -1));
+    const groups = partitionBy(subscriptions, (s) => (s.owner ? s.owner.__owl__.depth : -1));
     for (let group of groups) {
-      const proms = group.map(sub => sub.callback.call(sub.owner, rev));
+      const proms = group.map((sub) => sub.callback.call(sub.owner, rev));
       // at this point, each component in the current group has registered a
       // top level fiber in the scheduler. It could happen that rendering these
       // components is done (if they have no children).  This is why we manually
@@ -100,11 +100,11 @@ export class Context extends EventBus {
  * to context state changes. The `useContext` method returns the context state
  */
 export function useContext(ctx: Context): any {
-  const component: Component<any, any> = Component.current!;
+  const component: Component = Component.current!;
   return useContextWithCB(ctx, component, component.render.bind(component));
 }
 
-export function useContextWithCB(ctx: Context, component: Component<any, any>, method): any {
+export function useContextWithCB(ctx: Context, component: Component, method): any {
   const __owl__ = component.__owl__;
   const id = __owl__.id;
   const mapping = ctx.mapping;
@@ -115,31 +115,21 @@ export function useContextWithCB(ctx: Context, component: Component<any, any>, m
     __owl__.observer = new Observer();
     __owl__.observer.notifyCB = component.render.bind(component);
   }
-  const currentCB = __owl__.observer.notifyCB;
-  __owl__.observer.notifyCB = function() {
-    if (ctx.rev > mapping[id]) {
-      // in this case, the context has been updated since we were rendering
-      // last, and we do not need to render here with the observer. A
-      // rendering is coming anyway, with the correct props.
-      return;
-    }
-    currentCB();
-  };
 
   mapping[id] = 0;
   const renderFn = __owl__.renderFn;
-  __owl__.renderFn = function(comp, params) {
+  __owl__.renderFn = function (comp, params) {
     mapping[id] = ctx.rev;
     return renderFn(comp, params);
   };
-  ctx.on("update", component, async contextRev => {
+  ctx.on("update", component, async (contextRev) => {
     if (mapping[id] < contextRev) {
       mapping[id] = contextRev;
       await method();
     }
   });
   const __destroy = component.__destroy;
-  component.__destroy = parent => {
+  component.__destroy = (parent) => {
     ctx.off("update", component);
     delete mapping[id];
     __destroy.call(component, parent);

src/core/event_bus.ts

@@ -44,7 +44,7 @@ export class EventBus {
     }
     this.subscriptions[eventType].push({
       owner,
-      callback
+      callback,
     });
   }
 
@@ -54,7 +54,7 @@ export class EventBus {
   off(eventType: string, owner: any) {
     const subs = this.subscriptions[eventType];
     if (subs) {
-      this.subscriptions[eventType] = subs.filter(s => s.owner !== owner);
+      this.subscriptions[eventType] = subs.filter((s) => s.owner !== owner);
     }
   }
 

src/core/observer.ts

@@ -25,16 +25,13 @@ export class Observer {
   notifyCB() {}
 
   observe<T>(value: T, parent?: any): T {
-    if (value === null || typeof value !== "object" || value instanceof Date) {
-      // fun fact: typeof null === 'object'
-      return value;
-    }
     if (
-      value instanceof Map ||
-      value instanceof WeakMap ||
-      value instanceof Set ||
-      value instanceof WeakSet
+      value === null ||
+      typeof value !== "object" ||
+      value instanceof Date ||
+      value instanceof Promise
     ) {
+      // fun fact: typeof null === 'object'
       return value;
     }
     let metadata = this.weakMap.get(value) || this._observe(value, parent);
@@ -75,14 +72,14 @@ export class Observer {
           self.notifyCB();
         }
         return true;
-      }
+      },
     });
 
     const metadata = {
       value,
       proxy,
       rev: this.rev,
-      parent
+      parent,
     };
 
     this.weakMap.set(value, metadata);

src/core/owl_event.ts

@@ -7,7 +7,7 @@ import { Component } from "../component/component";
  */
 
 export class OwlEvent<T> extends CustomEvent<T> {
-  originalComponent: Component<any, any>;
+  originalComponent: Component;
   constructor(component, eventType, options) {
     super(eventType, options);
     this.originalComponent = component;

src/hooks.ts

@@ -1,4 +1,4 @@
-import { Component } from "./component/component";
+import { Component, Env } from "./component/component";
 import { Observer } from "./core/observer";
 
 /**
@@ -22,7 +22,7 @@ import { Observer } from "./core/observer";
  * trigger a rerendering of the current component.
  */
 export function useState<T>(state: T): T {
-  const component: Component<any, any> = Component.current!;
+  const component: Component = Component.current!;
   const __owl__ = component.__owl__;
   if (!__owl__.observer) {
     __owl__.observer = new Observer();
@@ -36,11 +36,11 @@ export function useState<T>(state: T): T {
 // -----------------------------------------------------------------------------
 function makeLifecycleHook(method: string, reverse: boolean = false) {
   if (reverse) {
-    return function(cb) {
-      const component: Component<any, any> = Component.current!;
+    return function (cb) {
+      const component: Component = Component.current!;
       if (component.__owl__[method]) {
         const current = component.__owl__[method];
-        component.__owl__[method] = function() {
+        component.__owl__[method] = function () {
           current.call(component);
           cb.call(component);
         };
@@ -49,11 +49,11 @@ function makeLifecycleHook(method: string, reverse: boolean = false) {
       }
     };
   } else {
-    return function(cb) {
-      const component: Component<any, any> = Component.current!;
+    return function (cb) {
+      const component: Component = Component.current!;
       if (component.__owl__[method]) {
         const current = component.__owl__[method];
-        component.__owl__[method] = function() {
+        component.__owl__[method] = function () {
           cb.call(component);
           current.call(component);
         };
@@ -65,12 +65,12 @@ function makeLifecycleHook(method: string, reverse: boolean = false) {
 }
 
 function makeAsyncHook(method: string) {
-  return function(cb) {
-    const component: Component<any, any> = Component.current!;
+  return function (cb) {
+    const component: Component = Component.current!;
     if (component.__owl__[method]) {
       const current = component.__owl__[method];
-      component.__owl__[method] = function(...args) {
-        return Promise.all[(current.call(component, ...args), cb.call(component, ...args))];
+      component.__owl__[method] = function (...args) {
+        return Promise.all([current.call(component, ...args), cb.call(component, ...args)]);
       };
     } else {
       component.__owl__[method] = cb;
@@ -94,12 +94,12 @@ export const onWillUpdateProps = makeAsyncHook("willUpdatePropsCB");
  * The purpose of this hook is to allow components to get a reference to a sub
  * html node or component.
  */
-interface Ref {
+interface Ref<C extends Component = Component> {
   el: HTMLElement | null;
-  comp: Component<any, any> | null;
+  comp: C | null;
 }
 
-export function useRef(name: string): Ref {
+export function useRef<C extends Component = Component>(name: string): Ref<C> {
   const __owl__ = Component.current!.__owl__;
   return {
     get el(): HTMLElement | null {
@@ -111,13 +111,33 @@ export function useRef(name: string): Ref {
       }
       return null;
     },
-    get comp(): Component<any, any> | null {
+    get comp(): C | null {
       const val = __owl__.refs && __owl__.refs[name];
-      return val instanceof Component ? val : null;
-    }
+      return val instanceof Component ? (val as C) : null;
+    },
   };
 }
 
+// -----------------------------------------------------------------------------
+// "Builder" hooks
+// -----------------------------------------------------------------------------
+
+/**
+ * This hook is useful as a building block for some customized hooks, that may
+ * need a reference to the component calling them.
+ */
+export function useComponent<P, E extends Env>(): Component<P, E> {
+  return Component.current as any;
+}
+
+/**
+ * This hook is useful as a building block for some customized hooks, that may
+ * need a reference to the env of the component calling them.
+ */
+export function useEnv<E extends Env>(): E {
+  return Component.current.env as any;
+}
+
 // -----------------------------------------------------------------------------
 // useSubEnv
 // -----------------------------------------------------------------------------
@@ -131,3 +151,32 @@ export function useSubEnv(nextEnv) {
   const component = Component.current!;
   component.env = Object.assign(Object.create(component.env), nextEnv);
 }
+
+// -----------------------------------------------------------------------------
+// useExternalListener
+// -----------------------------------------------------------------------------
+
+/**
+ * When a component needs to listen to DOM Events on element(s) that are not
+ * part of his hierarchy, we can use the `useExternalListener` hook.
+ * It will correctly add and remove the event listener, whenever the
+ * component is mounted and unmounted.
+ *
+ * Example:
+ *  a menu needs to listen to the click on window to be closed automatically
+ *
+ * Usage:
+ *  in the constructor of the OWL component that needs to be notified,
+ *  `useExternalListener(window, 'click', this._doSomething);`
+ * */
+export function useExternalListener(
+  target: HTMLElement | typeof window,
+  eventName: string,
+  handler,
+  eventParams?
+) {
+  const boundHandler = handler.bind(Component.current);
+
+  onMounted(() => target.addEventListener(eventName, boundHandler, eventParams));
+  onWillUnmount(() => target.removeEventListener(eventName, boundHandler, eventParams));
+}

src/index.ts

@@ -19,9 +19,10 @@ import { Link } from "./router/link";
 import { RouteComponent } from "./router/route_component";
 import { Router } from "./router/router";
 
-export { Component } from "./component/component";
+export { Component, mount } from "./component/component";
 export { QWeb };
 export { config };
+export { browser } from "./browser";
 
 export const Context = _context.Context;
 export const useState = _hooks.useState;
@@ -35,6 +36,7 @@ export const hooks = Object.assign({}, _hooks, {
   useContext: _context.useContext,
   useDispatch: _store.useDispatch,
   useGetters: _store.useGetters,
-  useStore: _store.useStore
+  useStore: _store.useStore,
 });
+
 export const __info__ = {};

src/misc/async_root.ts

@@ -10,7 +10,7 @@ import { xml } from "../tags";
  * from this coordination.  This is the goal of the AsyncRoot component.
  */
 
-export class AsyncRoot extends Component<any, any> {
+export class AsyncRoot extends Component {
   static template = xml`<t t-slot="default"/>`;
 
   async __updateProps(nextProps, parentFiber) {

src/misc/portal.ts

@@ -18,12 +18,16 @@ import { useSubEnv } from "../hooks";
  * are re-triggered on an empty <portal> node located in the parent's DOM.
  */
 
-export class Portal extends Component<any, any> {
+interface Props {
+  target: string;
+}
+
+export class Portal extends Component<Props> {
   static template = xml`<portal><t t-slot="default"/></portal>`;
   static props = {
     target: {
-      type: String
-    }
+      type: String,
+    },
   };
 
   // boolean to indicate whether or not we must listen to 'dom-appended' event
@@ -43,7 +47,7 @@ export class Portal extends Component<any, any> {
   // represents the element that is moved somewhere else
   portal: VNode | null = null;
   // the target where we will move `portal`
-  target: HTMLElement | null = null;
+  target: Element | null = null;
 
   constructor(parent, props) {
     super(parent, props);
@@ -51,12 +55,12 @@ export class Portal extends Component<any, any> {
     // put a callback in the env that is propagated to children s.t. portal can
     // register an handler to those events just before children will trigger them
     useSubEnv({
-      [portalSymbol]: ev => {
+      [portalSymbol]: (ev) => {
         if (!this._handledEvents.has(ev.type)) {
           this.portal!.elm!.addEventListener(ev.type, this._handlerTunnel);
           this._handledEvents.add(ev.type);
         }
-      }
+      },
     });
   }
   /**
@@ -120,7 +124,7 @@ export class Portal extends Component<any, any> {
    *
    * @override
    */
-  __patch(vnode) {
+  __patch(target, vnode) {
     if (this.doTargetLookUp) {
       const target = document.querySelector(this.props.target);
       if (!target) {
@@ -149,7 +153,7 @@ export class Portal extends Component<any, any> {
     this.portal = patch(portalPatch, vnode.children![0] as VNode);
     vnode.children = [];
 
-    super.__patch(vnode);
+    super.__patch(target, vnode);
 
     if (shouldDeploy) {
       this.__deployPortal();
@@ -158,7 +162,7 @@ export class Portal extends Component<any, any> {
   /**
    * Override to set the env
    */
-  __trigger(component: Component<any, any>, eventType: string, payload?: any) {
+  __trigger(component: Component, eventType: string, payload?: any) {
     const env = this.env;
     this.env = this.parentEnv;
     super.__trigger(component, eventType, payload);

src/qweb/base_directives.ts

@@ -1,6 +1,7 @@
-import { CompilationContext } from "./compilation_context";
+import { CompilationContext, INTERP_REGEXP } from "./compilation_context";
 import { QWeb } from "./qweb";
 import { htmlToVDOM } from "../vdom/html_to_vdom";
+import { QWebVar } from "./expression_parser";
 
 /**
  * Owl QWeb Directives
@@ -39,15 +40,16 @@ function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: Compilatio
   let exprID: string;
   if (typeof value === "string") {
     exprID = `_${ctx.generateID()}`;
-    ctx.addLine(`var ${exprID} = ${ctx.formatExpression(value)};`);
+    ctx.addLine(`let ${exprID} = ${ctx.formatExpression(value)};`);
   } else {
     exprID = `scope.${value.id}`;
   }
-  ctx.addIf(`${exprID} || ${exprID} === 0`);
+  ctx.addIf(`${exprID} != null`);
 
   if (ctx.escaping) {
     let protectID;
     if (value.hasBody) {
+      ctx.rootContext.shouldDefineUtils = true;
       protectID = ctx.startProtectScope();
       ctx.addLine(
         `${exprID} = ${exprID} instanceof utils.VDomArray ? utils.vDomToString(${exprID}) : ${exprID};`
@@ -61,7 +63,7 @@ function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: Compilatio
       let nodeID = ctx.generateID();
       ctx.rootContext.rootNode = nodeID;
       ctx.rootContext.parentTextNode = nodeID;
-      ctx.addLine(`var vn${nodeID} = {text: ${exprID}};`);
+      ctx.addLine(`let vn${nodeID} = {text: ${exprID}};`);
       if (ctx.rootContext.shouldDefineResult) {
         ctx.addLine(`result = vn${nodeID}`);
       }
@@ -95,7 +97,7 @@ QWeb.addDirective({
     let value = ctx.getValue(node.getAttribute("t-esc")!);
     compileValueNode(value, node, qweb, ctx.subContext("escaping", true));
     return true;
-  }
+  },
 });
 
 QWeb.addDirective({
@@ -105,7 +107,7 @@ QWeb.addDirective({
     let value = ctx.getValue(node.getAttribute("t-raw")!);
     compileValueNode(value, node, qweb, ctx);
     return true;
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -119,7 +121,7 @@ QWeb.addDirective({
     ctx.rootContext.shouldDefineScope = true;
     const variable = node.getAttribute("t-set")!;
     let value = node.getAttribute("t-value")!;
-    ctx.variables[variable] = ctx.variables[variable] || {};
+    ctx.variables[variable] = ctx.variables[variable] || ({} as QWebVar);
     let qwebvar = ctx.variables[variable];
     const hasBody = node.hasChildNodes();
 
@@ -127,7 +129,12 @@ QWeb.addDirective({
     qwebvar.expr = `scope.${variable}`;
     if (value) {
       const formattedValue = ctx.formatExpression(value);
-      ctx.addLine(`${qwebvar.expr} = ${formattedValue};`);
+      let scopeExpr = `scope`;
+      if (ctx.protectedScopeNumber) {
+        ctx.rootContext.shouldDefineUtils = true;
+        scopeExpr = `utils.getScope(scope, '${variable}')`;
+      }
+      ctx.addLine(`${scopeExpr}.${variable} = ${formattedValue};`);
       qwebvar.value = formattedValue;
     }
 
@@ -140,7 +147,7 @@ QWeb.addDirective({
       const _parentNode = ctx.parentNode;
       ctx.parentNode = tempParentNodeID;
 
-      ctx.addLine(`const c${tempParentNodeID} = new utils.VDomArray();`);
+      ctx.addLine(`let c${tempParentNodeID} = new utils.VDomArray();`);
       const nodeCopy = node.cloneNode(true) as Element;
       for (let attr of ["t-set", "t-value", "t-if", "t-else", "t-elif"]) {
         nodeCopy.removeAttribute(attr);
@@ -157,7 +164,7 @@ QWeb.addDirective({
       }
     }
     return true;
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -173,7 +180,7 @@ QWeb.addDirective({
   },
   finalize({ ctx }) {
     ctx.closeIf();
-  }
+  },
 });
 
 QWeb.addDirective({
@@ -189,7 +196,7 @@ QWeb.addDirective({
   },
   finalize({ ctx }) {
     ctx.closeIf();
-  }
+  },
 });
 
 QWeb.addDirective({
@@ -202,7 +209,7 @@ QWeb.addDirective({
   },
   finalize({ ctx }) {
     ctx.closeIf();
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -215,77 +222,91 @@ QWeb.addDirective({
     // Step 1: sanity checks
     // ------------------------------------------------
     ctx.rootContext.shouldDefineScope = true;
-    if (node.nodeName !== "t") {
-      throw new Error("Invalid tag for t-call directive (should be 't')");
-    }
+    ctx.rootContext.shouldDefineUtils = true;
     const subTemplate = node.getAttribute("t-call")!;
+    const isDynamic = INTERP_REGEXP.test(subTemplate);
     const nodeTemplate = qweb.templates[subTemplate];
-    if (!nodeTemplate) {
+    if (!isDynamic && !nodeTemplate) {
       throw new Error(`Cannot find template "${subTemplate}" (t-call)`);
     }
 
     // Step 2: compile target template in sub templates
     // ------------------------------------------------
-    if (!qweb.subTemplates[subTemplate]) {
-      qweb.subTemplates[subTemplate] = true;
-      const subTemplateFn = qweb._compile(subTemplate, nodeTemplate.elem, ctx);
-      qweb.subTemplates[subTemplate] = subTemplateFn;
+    let subIdstr: string;
+    if (isDynamic) {
+      const _id = ctx.generateID();
+      ctx.addLine(`let tname${_id} = ${ctx.interpolate(subTemplate)};`);
+      ctx.addLine(`let tid${_id} = this.subTemplates[tname${_id}];`);
+      ctx.addIf(`!tid${_id}`);
+      ctx.addLine(`tid${_id} = this.constructor.nextId++;`);
+      ctx.addLine(`this.subTemplates[tname${_id}] = tid${_id};`);
+      ctx.addLine(
+        `this.constructor.subTemplates[tid${_id}] = this._compile(tname${_id}, {hasParent: true, defineKey: true});`
+      );
+      ctx.closeIf();
+      subIdstr = `tid${_id}`;
+    } else {
+      let subId = qweb.subTemplates[subTemplate];
+      if (!subId) {
+        subId = QWeb.nextId++;
+        qweb.subTemplates[subTemplate] = subId;
+        const subTemplateFn = qweb._compile(subTemplate, { hasParent: true, defineKey: true });
+        QWeb.subTemplates[subId] = subTemplateFn;
+      }
+      subIdstr = `'${subId}'`;
     }
 
     // Step 3: compile t-call body if necessary
     // ------------------------------------------------
     let hasBody = node.hasChildNodes();
-    let protectID;
+    const protectID = ctx.startProtectScope();
     if (hasBody) {
       // we add a sub scope to protect the ambient scope
       ctx.addLine(`{`);
       ctx.indent();
-      protectID = ctx.startProtectScope();
       const nodeCopy = node.cloneNode(true) as Element;
       for (let attr of ["t-if", "t-else", "t-elif", "t-call"]) {
         nodeCopy.removeAttribute(attr);
       }
-      const parentNode = ctx.parentNode;
-      ctx.parentNode = "__0";
       // this local scope is intended to trap c__0
       ctx.addLine(`{`);
       ctx.indent();
       ctx.addLine("let c__0 = [];");
-      qweb._compileNode(nodeCopy, ctx);
+      qweb._compileNode(nodeCopy, ctx.subContext("parentNode", "__0"));
       ctx.rootContext.shouldDefineUtils = true;
       ctx.addLine("scope[utils.zero] = c__0;");
-      ctx.parentNode = parentNode;
       ctx.dedent();
       ctx.addLine(`}`);
     }
 
     // Step 4: add the appropriate function call to current component
     // ------------------------------------------------
-    const callingScope = hasBody ? "scope" : "Object.assign(Object.create(context), scope)";
+    const parentComponent = ctx.rootContext.shouldDefineParent
+      ? `parent`
+      : `utils.getComponent(context)`;
+    const key = ctx.generateTemplateKey();
+    const parentNode = ctx.parentNode ? `c${ctx.parentNode}` : "result";
+    const extra = `Object.assign({}, extra, {parentNode: ${parentNode}, parent: ${parentComponent}, key: ${key}})`;
     if (ctx.parentNode) {
-      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: c${ctx.parentNode}}));`
-      );
+      ctx.addLine(`this.constructor.subTemplates[${subIdstr}].call(this, scope, ${extra});`);
     } else {
       // this is a t-call with no parentnode, we need to extract the result
       ctx.rootContext.shouldDefineResult = true;
       ctx.addLine(`result = []`);
-      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: result}));`
-      );
+      ctx.addLine(`this.constructor.subTemplates[${subIdstr}].call(this, scope, ${extra});`);
       ctx.addLine(`result = result[0]`);
     }
 
     // Step 5: restore previous scope
     // ------------------------------------------------
     if (hasBody) {
-      ctx.stopProtectScope(protectID);
       ctx.dedent();
       ctx.addLine(`}`);
     }
+    ctx.stopProtectScope(protectID);
 
     return true;
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -301,17 +322,18 @@ QWeb.addDirective({
     const elems = node.getAttribute("t-foreach")!;
     const name = node.getAttribute("t-as")!;
     let arrayID = ctx.generateID();
-    ctx.addLine(`var _${arrayID} = ${ctx.formatExpression(elems)};`);
+    ctx.addLine(`let _${arrayID} = ${ctx.formatExpression(elems)};`);
     ctx.addLine(`if (!_${arrayID}) { throw new Error('QWeb error: Invalid loop expression')}`);
     let keysID = ctx.generateID();
     let valuesID = ctx.generateID();
-    ctx.addLine(`var _${keysID} = _${valuesID} = _${arrayID};`);
+    ctx.addLine(`let _${keysID} = _${arrayID};`);
+    ctx.addLine(`let _${valuesID} = _${arrayID};`);
     ctx.addIf(`!(_${arrayID} instanceof Array)`);
     ctx.addLine(`_${keysID} = Object.keys(_${arrayID});`);
     ctx.addLine(`_${valuesID} = Object.values(_${arrayID});`);
     ctx.closeIf();
-    ctx.addLine(`var _length${keysID} = _${keysID}.length;`);
-    let varsID = ctx.startProtectScope();
+    ctx.addLine(`let _length${keysID} = _${keysID}.length;`);
+    let varsID = ctx.startProtectScope(true);
     const loopVar = `i${ctx.loopNumber}`;
     ctx.addLine(`for (let ${loopVar} = 0; ${loopVar} < _length${keysID}; ${loopVar}++) {`);
     ctx.indent();
@@ -332,6 +354,13 @@ QWeb.addDirective({
         `Directive t-foreach should always be used with a t-key! (in template: '${ctx.templateName}')`
       );
     }
+    if (nodeCopy.hasAttribute("t-key")) {
+      const expr = ctx.formatExpression(nodeCopy.getAttribute("t-key")!);
+      ctx.addLine(`let key${ctx.loopNumber} = ${expr};`);
+      nodeCopy.removeAttribute("t-key");
+    } else {
+      ctx.addLine(`let key${ctx.loopNumber} = i${ctx.loopNumber};`);
+    }
 
     nodeCopy.removeAttribute("t-foreach");
     qweb._compileNode(nodeCopy, ctx);
@@ -339,7 +368,7 @@ QWeb.addDirective({
     ctx.addLine("}");
     ctx.stopProtectScope(varsID);
     return true;
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -350,7 +379,7 @@ QWeb.addDirective({
   priority: 1,
   atNodeEncounter({ ctx }) {
     ctx.addLine("debugger;");
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -362,5 +391,5 @@ QWeb.addDirective({
   atNodeEncounter({ ctx, value }) {
     const expr = ctx.formatExpression(value);
     ctx.addLine(`console.log(${expr})`);
-  }
+  },
 });

src/qweb/compilation_context.ts

@@ -1,4 +1,4 @@
-import { compileExpr, QWebVar } from "./expression_parser";
+import { compileExpr, compileExprToArray, QWebVar } from "./expression_parser";
 
 export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 //------------------------------------------------------------------------------
@@ -17,6 +17,7 @@ export class CompilationContext {
   rootContext: CompilationContext;
   shouldDefineParent: boolean = false;
   shouldDefineScope: boolean = false;
+  protectedScopeNumber: number = 0;
   shouldDefineQWeb: boolean = false;
   shouldDefineUtils: boolean = false;
   shouldDefineRefs: boolean = false;
@@ -26,12 +27,13 @@ export class CompilationContext {
   templateName: string;
   allowMultipleRoots: boolean = false;
   hasParentWidget: boolean = false;
-  currentKey: string = "";
+  hasKey0: boolean = false;
+  keyStack: boolean[] = [];
 
   constructor(name?: string) {
     this.rootContext = this;
     this.templateName = name || "noname";
-    this.addLine("var h = this.h;");
+    this.addLine("let h = this.h;");
   }
 
   generateID(): number {
@@ -48,20 +50,15 @@ export class CompilationContext {
    */
   generateTemplateKey(prefix: string = ""): string {
     const id = this.generateID();
-    if (this.loopNumber === 0 && !this.currentKey) {
+    if (this.loopNumber === 0 && !this.hasKey0) {
       return `'${prefix}__${id}__'`;
     }
-    let locationExpr = `\`${prefix}__${id}__`;
-    for (let i = 0; i < this.loopNumber - 1; i++) {
-      locationExpr += `\${i${i + 1}}__`;
-    }
-    if (this.currentKey) {
-      const k = this.currentKey;
-      this.addLine(`let k${id} = ${locationExpr}\` + ${k};`);
-    } else {
-      locationExpr += this.loopNumber ? `\${i${this.loopNumber}}__\`` : "`";
-      this.addLine(`let k${id} = ${locationExpr};`);
+    let key = `\`${prefix}__${id}__`;
+    let start = this.hasKey0 ? 0 : 1;
+    for (let i = start; i < this.loopNumber + 1; i++) {
+      key += `\${key${i}}__`;
     }
+    this.addLine(`let k${id} = ${key}\`;`);
     return `k${id}`;
   }
 
@@ -116,11 +113,11 @@ export class CompilationContext {
   }
 
   indent() {
-    this.indentLevel++;
+    this.rootContext.indentLevel++;
   }
 
   dedent() {
-    this.indentLevel--;
+    this.rootContext.indentLevel--;
   }
 
   addLine(line: string): number {
@@ -159,6 +156,35 @@ export class CompilationContext {
     this.rootContext.shouldDefineScope = true;
     return compileExpr(expr, this.variables);
   }
+  captureExpression(expr: string): string {
+    this.rootContext.shouldDefineScope = true;
+    const argId = this.generateID();
+    const tokens = compileExprToArray(expr, this.variables);
+    const done = new Set();
+    return tokens
+      .map((tok) => {
+        // "this" in captured expressions should be the current component
+        if (tok.value === "this") {
+          if (!done.has("this")) {
+            done.add("this");
+            this.addLine(`const this_${argId} = utils.getComponent(context);`);
+          }
+          tok.value = `this_${argId}`;
+        }
+        // Variables that should be looked up in the scope. isLocal is for arrow
+        // function arguments that should stay untouched (eg "ev => ev" should
+        // not become "const ev_1 = scope['ev']; ev_1 => ev_1")
+        if (tok.varName && !tok.isLocal) {
+          if (!done.has(tok.varName)) {
+            done.add(tok.varName);
+            this.addLine(`const ${tok.varName}_${argId} = ${tok.value};`);
+          }
+          tok.value = `${tok.varName}_${argId}`;
+        }
+        return tok.value;
+      })
+      .join("");
+  }
 
   /**
    * Perform string interpolation on the given string. Note that if the whole
@@ -174,17 +200,23 @@ export class CompilationContext {
       return `(${this.formatExpression(s.slice(2, -2))})`;
     }
 
-    let r = s.replace(/\{\{.*?\}\}/g, s => "${" + this.formatExpression(s.slice(2, -2)) + "}");
+    let r = s.replace(/\{\{.*?\}\}/g, (s) => "${" + this.formatExpression(s.slice(2, -2)) + "}");
     return "`" + r + "`";
   }
-  startProtectScope(): number {
+  startProtectScope(codeBlock?: boolean): number {
     const protectID = this.generateID();
+    this.rootContext.protectedScopeNumber++;
     this.rootContext.shouldDefineScope = true;
-    this.addLine(`const _origScope${protectID} = scope;`);
-    this.addLine(`scope = Object.assign(Object.create(context), scope);`);
+    const scopeExpr = `Object.create(scope);`;
+    this.addLine(`let _origScope${protectID} = scope;`);
+    this.addLine(`scope = ${scopeExpr}`);
+    if (!codeBlock) {
+      this.addLine(`scope.__access_mode__ = 'ro';`);
+    }
     return protectID;
   }
   stopProtectScope(protectID: number) {
+    this.rootContext.protectedScopeNumber--;
     this.addLine(`scope = _origScope${protectID};`);
   }
 }

src/qweb/expression_parser.ts

@@ -25,18 +25,19 @@
 // Misc types, constants and helpers
 //------------------------------------------------------------------------------
 
-const RESERVED_WORDS = "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,eval,void,Math,RegExp,Array,Object,Date".split(
-  ","
-);
+const RESERVED_WORDS =
+  "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,eval,void,Math,RegExp,Array,Object,Date".split(
+    ","
+  );
 
-const WORD_REPLACEMENT = {
+const WORD_REPLACEMENT = Object.assign(Object.create(null), {
   and: "&&",
   or: "||",
   gt: ">",
   gte: ">=",
   lt: "<",
-  lte: "<="
-};
+  lte: "<=",
+});
 
 export interface QWebVar {
   id: string; // foo
@@ -57,6 +58,7 @@ type TKind =
   | "RIGHT_PAREN"
   | "COMMA"
   | "VALUE"
+  | "TEMPLATE_STRING"
   | "SYMBOL"
   | "OPERATOR"
   | "COLON";
@@ -66,9 +68,12 @@ interface Token {
   value: string;
   originalValue?: string;
   size?: number;
+  varName?: string;
+  replace?: Function;
+  isLocal?: boolean;
 }
 
-const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
+const STATIC_TOKEN_MAP: { [key: string]: TKind } = Object.assign(Object.create(null), {
   "{": "LEFT_BRACE",
   "}": "RIGHT_BRACE",
   "[": "LEFT_BRACKET",
@@ -76,19 +81,19 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
   ":": "COLON",
   ",": "COMMA",
   "(": "LEFT_PAREN",
-  ")": "RIGHT_PAREN"
-};
+  ")": "RIGHT_PAREN",
+});
 
 // note that the space after typeof is relevant. It makes sure that the formatted
 // expression has a space after typeof
-const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;".split(",");
+const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ".split(",");
 
 type Tokenizer = (expr: string) => Token | false;
 
-let tokenizeString: Tokenizer = function(expr) {
+let tokenizeString: Tokenizer = function (expr) {
   let s = expr[0];
   let start = s;
-  if (s !== "'" && s !== '"') {
+  if (s !== "'" && s !== '"' && s !== "`") {
     return false;
   }
   let i = 1;
@@ -110,10 +115,21 @@ let tokenizeString: Tokenizer = function(expr) {
     throw new Error("Invalid expression");
   }
   s += start;
+  if (start === "`") {
+    return {
+      type: "TEMPLATE_STRING",
+      value: s,
+      replace(replacer) {
+        return s.replace(/\$\{(.*?)\}/g, (match, group) => {
+          return "${" + replacer(group) + "}";
+        });
+      },
+    };
+  }
   return { type: "VALUE", value: s };
 };
 
-let tokenizeNumber: Tokenizer = function(expr) {
+let tokenizeNumber: Tokenizer = function (expr) {
   let s = expr[0];
   if (s && s.match(/[0-9]/)) {
     let i = 1;
@@ -127,7 +143,7 @@ let tokenizeNumber: Tokenizer = function(expr) {
   }
 };
 
-let tokenizeSymbol: Tokenizer = function(expr) {
+let tokenizeSymbol: Tokenizer = function (expr) {
   let s = expr[0];
   if (s && s.match(/[a-zA-Z_\$]/)) {
     let i = 1;
@@ -144,7 +160,7 @@ let tokenizeSymbol: Tokenizer = function(expr) {
   }
 };
 
-const tokenizeStatic: Tokenizer = function(expr) {
+const tokenizeStatic: Tokenizer = function (expr) {
   const char = expr[0];
   if (char && char in STATIC_TOKEN_MAP) {
     return { type: STATIC_TOKEN_MAP[char], value: char };
@@ -152,7 +168,7 @@ const tokenizeStatic: Tokenizer = function(expr) {
   return false;
 };
 
-const tokenizeOperator: Tokenizer = function(expr) {
+const tokenizeOperator: Tokenizer = function (expr) {
   for (let op of OPERATORS) {
     if (expr.startsWith(op)) {
       return { type: "OPERATOR", value: op };
@@ -166,7 +182,7 @@ const TOKENIZERS = [
   tokenizeNumber,
   tokenizeOperator,
   tokenizeSymbol,
-  tokenizeStatic
+  tokenizeStatic,
 ];
 
 /**
@@ -209,6 +225,10 @@ export function tokenize(expr: string): Token[] {
 // Expression "evaluator"
 //------------------------------------------------------------------------------
 
+const isLeftSeparator = (token) => token && (token.type === "LEFT_BRACE" || token.type === "COMMA");
+const isRightSeparator = (token) =>
+  token && (token.type === "RIGHT_BRACE" || token.type === "COMMA");
+
 /**
  * This is the main function exported by this file. This is the code that will
  * process an expression (given as a string) and returns another expression with
@@ -234,16 +254,43 @@ export function tokenize(expr: string): Token[] {
  * the arrow operator, then we add the current (or some previous tokens) token to
  * the list of variables so it does not get replaced by a lookup in the context
  */
-export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
+export function compileExprToArray(expr: string, scope: { [key: string]: QWebVar }): Token[] {
+  const localVars = new Set<string>();
   scope = Object.create(scope);
   const tokens = tokenize(expr);
-  for (let i = 0; i < tokens.length; i++) {
+
+  let i = 0;
+  let stack = []; // to track last opening [ or {
+
+  while (i < tokens.length) {
     let token = tokens[i];
     let prevToken = tokens[i - 1];
     let nextToken = tokens[i + 1];
+    let groupType = stack[stack.length - 1];
+
+    switch (token.type) {
+      case "LEFT_BRACE":
+      case "LEFT_BRACKET":
+        stack.push(token.type);
+        break;
+      case "RIGHT_BRACE":
+      case "RIGHT_BRACKET":
+        stack.pop();
+    }
+
     let isVar = token.type === "SYMBOL" && !RESERVED_WORDS.includes(token.value);
     if (token.type === "SYMBOL" && !RESERVED_WORDS.includes(token.value)) {
       if (prevToken) {
+        // normalize missing tokens: {a} should be equivalent to {a:a}
+        if (
+          groupType === "LEFT_BRACE" &&
+          isLeftSeparator(prevToken) &&
+          isRightSeparator(nextToken)
+        ) {
+          tokens.splice(i + 1, 0, { type: "COLON", value: ":" }, { ...token });
+          nextToken = tokens[i + 1];
+        }
+
         if (prevToken.type === "OPERATOR" && prevToken.value === ".") {
           isVar = false;
         } else if (prevToken.type === "LEFT_BRACE" || prevToken.type === "COMMA") {
@@ -253,6 +300,9 @@ export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): st
         }
       }
     }
+    if (token.type === "TEMPLATE_STRING") {
+      token.value = token.replace((expr) => compileExpr(expr, scope));
+    }
     if (nextToken && nextToken.type === "OPERATOR" && nextToken.value === "=>") {
       if (token.type === "RIGHT_PAREN") {
         let j = i - 1;
@@ -260,15 +310,18 @@ export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): st
           if (tokens[j].type === "SYMBOL" && tokens[j].originalValue) {
             tokens[j].value = tokens[j].originalValue!;
             scope[tokens[j].value] = { id: tokens[j].value, expr: tokens[j].value };
+            localVars.add(tokens[j].value);
           }
           j--;
         }
       } else {
         scope[token.value] = { id: token.value, expr: token.value };
+        localVars.add(token.value);
       }
     }
 
     if (isVar) {
+      token.varName = token.value;
       if (token.value in scope && "id" in scope[token.value]) {
         token.value = scope[token.value].expr!;
       } else {
@@ -276,6 +329,20 @@ export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): st
         token.value = `scope['${token.value}']`;
       }
     }
+    i++;
   }
-  return tokens.map(t => t.value).join("");
+  // Mark all variables that have been used locally.
+  // This assumes the expression has only one scope (incorrect but "good enough for now")
+  for (const token of tokens) {
+    if (token.type === "SYMBOL" && localVars.has(token.value)) {
+      token.isLocal = true;
+    }
+  }
+  return tokens;
+}
+
+export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
+  return compileExprToArray(expr, scope)
+    .map((t) => t.value)
+    .join("");
 }

src/qweb/extensions.ts

@@ -1,5 +1,8 @@
+import { STATUS } from "../component/component";
 import { VNode } from "../vdom/index";
+import { INTERP_REGEXP } from "./compilation_context";
 import { QWeb } from "./qweb";
+import { browser } from "../browser";
 
 /**
  * Owl QWeb Extensions
@@ -23,7 +26,7 @@ import { QWeb } from "./qweb";
 export const MODS_CODE = {
   prevent: "e.preventDefault();",
   self: "if (e.target !== this.elm) {return}",
-  stop: "e.stopPropagation();"
+  stop: "e.stopPropagation();",
 };
 
 interface HandlerInfo {
@@ -40,14 +43,17 @@ export function makeHandlerCode(
   putInCache: boolean,
   modcodes = MODS_CODE
 ): HandlerInfo {
-  const [event, ...mods] = fullName.slice(5).split(".");
+  let [event, ...mods] = fullName.slice(5).split(".");
+  if (mods.includes("capture")) {
+    event = "!" + event;
+  }
   if (!event) {
     throw new Error("Missing event name with t-on directive");
   }
   let code: string;
   // check if it is a method with no args, a method with args or an expression
   let args: string = "";
-  const name: string = value.replace(/\(.*\)/, function(_args) {
+  const name: string = value.replace(/\(.*\)/, function (_args) {
     args = _args.slice(1, -1);
     return "";
   });
@@ -58,7 +64,7 @@ export function makeHandlerCode(
     ctx.rootContext.shouldDefineUtils = true;
     const comp = `utils.getComponent(context)`;
     if (args) {
-      let argId = ctx.generateID();
+      const argId = ctx.generateID();
       ctx.addLine(`let args${argId} = [${ctx.formatExpression(args)}];`);
       code = `${comp}['${name}'](...args${argId}, e);`;
       putInCache = false;
@@ -67,11 +73,13 @@ export function makeHandlerCode(
     }
   } else {
     // if we get here, then it is an expression
+    // we need to capture every variable in it
     putInCache = false;
-    code = ctx.formatExpression(value);
+    code = ctx.captureExpression(value);
+    code = `const res = (() => { return ${code} })(); if (typeof res === 'function') { res(e) }`;
   }
-  const modCode = mods.map(mod => modcodes[mod]).join("");
-  let handler = `function (e) {if (!context.__owl__.isMounted){return}${modCode}${code}}`;
+  const modCode = mods.map((mod) => modcodes[mod]).join("");
+  let handler = `function (e) {if (context.__owl__.status === ${STATUS.DESTROYED}){return}${modCode}${code}}`;
   if (putInCache) {
     const key = ctx.generateTemplateKey(event);
     ctx.addLine(`extra.handlers[${key}] = extra.handlers[${key}] || ${handler};`);
@@ -86,7 +94,7 @@ QWeb.addDirective({
   atNodeCreation({ ctx, fullName, value, nodeID }) {
     const { event, handler } = makeHandlerCode(ctx, fullName, value, true);
     ctx.addLine(`p${nodeID}.on['${event}'] = ${handler};`);
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -101,17 +109,17 @@ QWeb.addDirective({
     ctx.addLine(`const ${refKey} = ${ctx.interpolate(value)};`);
     addNodeHook("create", `context.__owl__.refs[${refKey}] = n.elm;`);
     addNodeHook("destroy", `delete context.__owl__.refs[${refKey}];`);
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
 // t-transition
 //------------------------------------------------------------------------------
-QWeb.utils.nextFrame = function(cb: () => void) {
+QWeb.utils.nextFrame = function (cb: () => void) {
   requestAnimationFrame(() => requestAnimationFrame(cb));
 };
 
-QWeb.utils.transitionInsert = function(vn: VNode, name: string) {
+QWeb.utils.transitionInsert = function (vn: VNode, name: string) {
   const elm = <HTMLElement>vn.elm;
   // remove potential duplicated vnode that is currently being removed, to
   // prevent from having twice the same node in the DOM during an animation
@@ -135,7 +143,7 @@ QWeb.utils.transitionInsert = function(vn: VNode, name: string) {
   });
 };
 
-QWeb.utils.transitionRemove = function(vn: VNode, name: string, rm: () => void) {
+QWeb.utils.transitionRemove = function (vn: VNode, name: string, rm: () => void) {
   const elm = <HTMLElement>vn.elm;
   elm.setAttribute("data-owl-key", vn.key!);
 
@@ -179,12 +187,26 @@ function toMs(s: string): number {
 }
 
 function whenTransitionEnd(elm: HTMLElement, cb) {
+  if (!elm.parentNode) {
+    // if we get here, this means that the element was removed for some other
+    // reasons, and in that case, we don't want to work on animation since nothing
+    // will be displayed anyway.
+    return;
+  }
+
   const styles = window.getComputedStyle(elm);
   const delays: Array<string> = (styles.transitionDelay || "").split(", ");
   const durations: Array<string> = (styles.transitionDuration || "").split(", ");
   const timeout: number = getTimeout(delays, durations);
   if (timeout > 0) {
-    elm.addEventListener("transitionend", cb, { once: true });
+    const transitionEndCB = () => {
+      if (!elm.parentNode) return;
+      cb();
+      browser.clearTimeout(fallbackTimeout);
+      elm.removeEventListener("transitionend", transitionEndCB);
+    };
+    elm.addEventListener("transitionend", transitionEndCB, { once: true });
+    const fallbackTimeout = browser.setTimeout(transitionEndCB, timeout + 1);
   } else {
     cb();
   }
@@ -194,16 +216,19 @@ QWeb.addDirective({
   name: "transition",
   priority: 96,
   atNodeCreation({ ctx, value, addNodeHook }) {
+    if (!QWeb.enableTransitions) {
+      return;
+    }
     ctx.rootContext.shouldDefineUtils = true;
     let name = value;
     const hooks = {
       insert: `utils.transitionInsert(vn, '${name}');`,
-      remove: `utils.transitionRemove(vn, '${name}', rm);`
+      remove: `utils.transitionRemove(vn, '${name}', rm);`,
     };
     for (let hookName in hooks) {
       addNodeHook(hookName, hooks[hookName]);
     }
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -214,8 +239,9 @@ QWeb.addDirective({
   priority: 80,
   atNodeEncounter({ ctx, value, node, qweb }): boolean {
     const slotKey = ctx.generateID();
+    const valueExpr = value.match(INTERP_REGEXP) ? ctx.interpolate(value) : `'${value}'`;
     ctx.addLine(
-      `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + '${value}'];`
+      `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + ${valueExpr}];`
     );
     ctx.addIf(`slot${slotKey}`);
     let parentNode = `c${ctx.parentNode}`;
@@ -240,17 +266,20 @@ QWeb.addDirective({
     }
     ctx.closeIf();
     return true;
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
 // t-model
 //------------------------------------------------------------------------------
-QWeb.utils.toNumber = function(val: string): number | string {
+QWeb.utils.toNumber = function (val: string): number | string {
   const n = parseFloat(val);
   return isNaN(n) ? val : n;
 };
 
+const hasDotAtTheEnd = /\.[\w_]+\s*$/;
+const hasBracketsAtTheEnd = /\[[^\[]+\]\s*$/;
+
 QWeb.addDirective({
   name: "model",
   priority: 42,
@@ -259,15 +288,41 @@ QWeb.addDirective({
     let handler;
     let event = fullName.includes(".lazy") ? "change" : "input";
 
-    // we keep here a reference to the "base expression" (if the expression
-    // is `t-model="some.expr.value", then the base expression is "some.expr").
-    // This is necessary so we can capture it in the handler closure.
-    let expr = ctx.formatExpression(value);
-    const index = expr.lastIndexOf(".");
-    const baseExpr = expr.slice(0, index);
-    ctx.addLine(`let expr${nodeID} = ${baseExpr};`);
+    // First step: we need to understand the structure of the expression, and
+    // from it, extract a base expression (that we can capture, which is
+    // important because it will be used in a handler later) and a formatted
+    // expression (which uses the captured base expression)
+    //
+    // Also, we support 2 kinds of values: some.expr.value or some.expr[value]
+    // For the first one, we have:
+    // - base expression = scope[some].expr
+    // - expression = exprX.value (where exprX is the var that captures the base expr)
+    // and for the expression with brackets:
+    // - base expression = scope[some].expr
+    // - expression = exprX[keyX] (where exprX is the var that captures the base expr
+    //        and keyX captures scope[value])
+    let expr: string;
+    let baseExpr: string;
+
+    if (hasDotAtTheEnd.test(value)) {
+      // we manage the case where the expr has a dot: some.expr.value
+      const index = value.lastIndexOf(".");
+      baseExpr = value.slice(0, index);
+      ctx.addLine(`let expr${nodeID} = ${ctx.formatExpression(baseExpr)};`);
+      expr = `expr${nodeID}${value.slice(index)}`;
+    } else if (hasBracketsAtTheEnd.test(value)) {
+      // we manage here the case where the expr ends in a bracket expression:
+      //    some.expr[value]
+      const index = value.lastIndexOf("[");
+      baseExpr = value.slice(0, index);
+      ctx.addLine(`let expr${nodeID} = ${ctx.formatExpression(baseExpr)};`);
+      let exprKey = value.trimRight().slice(index + 1, -1);
+      ctx.addLine(`let exprKey${nodeID} = ${ctx.formatExpression(exprKey)};`);
+      expr = `expr${nodeID}[exprKey${nodeID}]`;
+    } else {
+      throw new Error(`Invalid t-model expression: "${value}" (it should be assignable)`);
+    }
 
-    expr = `expr${nodeID}.${expr.slice(index + 1)}`;
     const key = ctx.generateTemplateKey();
     if (node.tagName === "select") {
       ctx.addLine(`p${nodeID}.props = {value: ${expr}};`);
@@ -294,7 +349,7 @@ QWeb.addDirective({
     }
     ctx.addLine(`extra.handlers[${key}] = extra.handlers[${key}] || (${handler});`);
     ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers[${key}];`);
-  }
+  },
 });
 
 //------------------------------------------------------------------------------
@@ -303,9 +358,20 @@ QWeb.addDirective({
 QWeb.addDirective({
   name: "key",
   priority: 45,
-  atNodeEncounter({ ctx, value }) {
-    let id = ctx.generateID();
-    ctx.addLine(`const nodeKey${id} = ${ctx.formatExpression(value)};`);
-    ctx.currentKey = `nodeKey${id}`;
-  }
+  atNodeEncounter({ ctx, value, node }) {
+    if (ctx.loopNumber === 0) {
+      ctx.keyStack.push(ctx.rootContext.hasKey0);
+      ctx.rootContext.hasKey0 = true;
+    }
+    ctx.addLine("{");
+    ctx.indent();
+    ctx.addLine(`let key${ctx.loopNumber} = ${ctx.formatExpression(value)};`);
+  },
+  finalize({ ctx }) {
+    ctx.dedent();
+    ctx.addLine("}");
+    if (ctx.loopNumber === 0) {
+      ctx.rootContext.hasKey0 = ctx.keyStack.pop() as boolean;
+    }
+  },
 });

src/qweb/qweb.ts

@@ -66,67 +66,126 @@ interface QWebConfig {
 // Const/global stuff/helpers
 //------------------------------------------------------------------------------
 
-const DISABLED_TAGS = ["input", "textarea", "button", "select", "option", "optgroup"];
-
-const TRANSLATABLE_ATTRS = ["label", "title", "placeholder", "alt"];
+export const TRANSLATABLE_ATTRS = ["label", "title", "placeholder", "alt"];
 
 const lineBreakRE = /[\r\n]/;
 const whitespaceRE = /\s+/g;
+const translationRE = /^(\s*)([\s\S]+?)(\s*)$/;
 
 const NODE_HOOKS_PARAMS = {
   create: "(_, n)",
   insert: "vn",
   remove: "(vn, rm)",
-  destroy: "()"
+  destroy: "()",
 };
 
 interface Utils {
-  toObj(expr: any): Object;
+  toClassObj(expr: any): Object;
   shallowEqual(p1: Object, p2: Object): boolean;
   [key: string]: any;
 }
 
+function isComponent(obj): boolean {
+  return obj && obj.hasOwnProperty("__owl__");
+}
+
+class VDomArray extends Array {
+  toString() {
+    return vDomToString(this);
+  }
+}
+
+function vDomToString(vdom: VNode[]): string {
+  return vdom
+    .map((vnode) => {
+      if (vnode.sel) {
+        const node = document.createElement(vnode.sel);
+        const result = patch(node, vnode);
+        return (<HTMLElement>result.elm).outerHTML;
+      } else {
+        return vnode.text;
+      }
+    })
+    .join("");
+}
+
 const UTILS: Utils = {
   zero: Symbol("zero"),
-  toObj(expr) {
+  toClassObj(expr) {
+    const result = {};
     if (typeof expr === "string") {
+      // we transform here a list of classes into an object:
+      //  'hey you' becomes {hey: true, you: true}
       expr = expr.trim();
       if (!expr) {
         return {};
       }
       let words = expr.split(/\s+/);
-      let result = {};
       for (let i = 0; i < words.length; i++) {
         result[words[i]] = true;
       }
       return result;
     }
-    return expr;
+    // this is already an object, but we may need to split keys:
+    // {'a b': true, 'a c': false} should become {a: true, b: true, c: false}
+    for (let key in expr) {
+      const value = expr[key];
+      const words = key.split(/\s+/);
+      for (let word of words) {
+        result[word] = result[word] || value;
+      }
+    }
+    return result;
+  },
+  /**
+   * This method combines the current context with the variables defined in a
+   * scope for use in a slot.
+   *
+   * The implementation is kind of tricky because we want to preserve the
+   * prototype chain structure of the cloned result. So we need to traverse the
+   * prototype chain, cloning each level respectively.
+   */
+  combine(context, scope) {
+    let clone = context;
+    const scopeStack = [];
+    while (!isComponent(scope)) {
+      scopeStack.push(scope);
+      scope = scope.__proto__;
+    }
+    while (scopeStack.length) {
+      let scope = scopeStack.pop();
+      clone = Object.create(clone);
+      Object.assign(clone, scope);
+    }
+    return clone;
   },
   shallowEqual,
   addNameSpace(vnode) {
     addNS(vnode.data, vnode.children, vnode.sel);
   },
-  VDomArray: class VDomArray extends Array {},
-  vDomToString: function(vdom: VNode[]): string {
-    return vdom
-      .map(vnode => {
-        if (vnode.sel) {
-          const node = document.createElement(vnode.sel);
-          const result = patch(node, vnode);
-          return (<HTMLElement>result.elm).outerHTML;
-        } else {
-          return vnode.text;
-        }
-      })
-      .join();
-  },
+  VDomArray,
+  vDomToString,
   getComponent(obj) {
-    while (obj && !obj.hasOwnProperty("__owl__")) {
+    while (obj && !isComponent(obj)) {
       obj = obj.__proto__;
     }
     return obj;
-  }
+  },
+  getScope(obj, property: string) {
+    const obj0 = obj;
+    while (
+      obj &&
+      !obj.hasOwnProperty(property) &&
+      !(obj.hasOwnProperty("__access_mode__") && obj.__access_mode__ === "ro")
+    ) {
+      const newObj = obj.__proto__;
+      if (!newObj || isComponent(newObj)) {
+        return obj0;
+      }
+      obj = newObj;
+    }
+    return obj;
+  },
 };
 
 function parseXML(xml: string): Document {
@@ -159,6 +218,10 @@ function parseXML(xml: string): Document {
   return doc;
 }
 
+function escapeQuotes(str: string): string {
+  return str.replace(/\'/g, "\\'");
+}
+
 //------------------------------------------------------------------------------
 // QWeb rendering engine
 //------------------------------------------------------------------------------
@@ -172,7 +235,8 @@ export class QWeb extends EventBus {
     name: 1,
     att: 1,
     attf: 1,
-    translation: 1
+    translation: 1,
+    tag: 1,
   };
   static DIRECTIVES: Directive[] = [];
 
@@ -183,16 +247,19 @@ export class QWeb extends EventBus {
   h = h;
   // dev mode enables better error messages or more costly validations
   static dev: boolean = false;
+  static enableTransitions: boolean = true;
 
   // slots contains sub templates defined with t-set inside t-component nodes, and
   // are meant to be used by the t-slot directive.
   static slots = {};
   static nextSlotId = 1;
 
-  // recursiveTemplates contains sub templates called with t-call, but which
-  // ends up in recursive situations.  This is very similar to the slot situation,
-  // as in we need to propagate the scope.
-  subTemplates = {};
+  // subTemplates are stored in two objects: a (local) mapping from a name to an
+  // id, and a (global) mapping from an id to the compiled function.  This is
+  // necessary to ensure that global templates can be called with more than one
+  // QWeb instance.
+  subTemplates: { [key: string]: number } = {};
+  static subTemplates: { [id: number]: Function } = {};
 
   isUpdating: boolean = false;
   translateFn?: QWebConfig["translateFn"];
@@ -216,7 +283,7 @@ export class QWeb extends EventBus {
     QWeb.DIRECTIVE_NAMES[directive.name] = 1;
     QWeb.DIRECTIVES.sort((d1, d2) => d1.priority - d2.priority);
     if (directive.extraNames) {
-      directive.extraNames.forEach(n => (QWeb.DIRECTIVE_NAMES[n] = 1));
+      directive.extraNames.forEach((n) => (QWeb.DIRECTIVE_NAMES[n] = 1));
     }
   }
 
@@ -262,6 +329,9 @@ export class QWeb extends EventBus {
    * template, with the name given by the t-name attribute.
    */
   addTemplates(xmlstr: string | Document) {
+    if (!xmlstr) {
+      return;
+    }
     const doc = typeof xmlstr === "string" ? parseXML(xmlstr) : xmlstr;
     const templates = doc.getElementsByTagName("templates")[0];
     if (!templates) {
@@ -280,11 +350,11 @@ export class QWeb extends EventBus {
     this._processTemplate(elem);
     const template = {
       elem,
-      fn: function(this: QWeb, context, extra) {
-        const compiledFunction = this._compile(name, elem);
+      fn: function (this: QWeb, context, extra) {
+        const compiledFunction = this._compile(name);
         template.fn = compiledFunction;
         return compiledFunction.call(this, context, extra);
-      }
+      },
     };
     this.templates[name] = template;
   }
@@ -294,10 +364,10 @@ export class QWeb extends EventBus {
     for (let i = 0, ilen = tbranch.length; i < ilen; i++) {
       let node = tbranch[i];
       let prevElem = node.previousElementSibling!;
-      let pattr = function(name) {
+      let pattr = function (name) {
         return prevElem.getAttribute(name);
       };
-      let nattr = function(name) {
+      let nattr = function (name) {
         return +!!node.getAttribute(name);
       };
       if (prevElem && (pattr("t-if") || pattr("t-elif"))) {
@@ -307,16 +377,17 @@ export class QWeb extends EventBus {
           );
         }
         if (
-          ["t-if", "t-elif", "t-else"].map(nattr).reduce(function(a, b) {
+          ["t-if", "t-elif", "t-else"].map(nattr).reduce(function (a, b) {
             return a + b;
           }) > 1
         ) {
           throw new Error("Only one conditional branching directive is allowed per node");
         }
-        // All text nodes between branch nodes are removed
+        // All text (with only spaces) and comment nodes (nodeType 8) between
+        // branch nodes are removed
         let textNode;
         while ((textNode = node.previousSibling) !== prevElem) {
-          if (textNode.nodeValue.trim().length) {
+          if (textNode.nodeValue.trim().length && textNode.nodeType !== 8) {
             throw new Error("text is not allowed between branching directives");
           }
           textNode.remove();
@@ -383,23 +454,36 @@ export class QWeb extends EventBus {
     });
   }
 
-  _compile(name: string, elem: Element, parentContext?: CompilationContext): CompiledTemplate {
+  _compile(
+    name: string,
+    options: {
+      elem?: Element;
+      hasParent?: boolean;
+      defineKey?: boolean;
+    } = {}
+  ): CompiledTemplate {
+    const elem = options.elem || this.templates[name].elem;
     const isDebug = elem.attributes.hasOwnProperty("t-debug");
     const ctx = new CompilationContext(name);
     if (elem.tagName !== "t") {
       ctx.shouldDefineResult = false;
     }
-    if (parentContext) {
-      ctx.variables = Object.create(parentContext.variables);
-      ctx.parentNode = parentContext.parentNode || ctx.generateID();
+    if (options.hasParent) {
+      ctx.variables = Object.create(null);
+      ctx.parentNode = ctx.generateID();
       ctx.allowMultipleRoots = true;
+      ctx.shouldDefineParent = true;
       ctx.hasParentWidget = true;
       ctx.shouldDefineResult = false;
       ctx.addLine(`let c${ctx.parentNode} = extra.parentNode;`);
+      if (options.defineKey) {
+        ctx.addLine(`let key0 = extra.key || "";`);
+        ctx.hasKey0 = true;
+      }
     }
     this._compileNode(elem, ctx);
 
-    if (!parentContext) {
+    if (!options.hasParent) {
       if (ctx.shouldDefineResult) {
         ctx.addLine(`return result;`);
       } else {
@@ -451,7 +535,8 @@ export class QWeb extends EventBus {
       }
       if (this.translateFn) {
         if ((node.parentNode as any).getAttribute("t-translation") !== "off") {
-          text = this.translateFn(text);
+          const match = translationRE.exec(text);
+          text = match[1] + this.translateFn(match[2]) + match[3];
         }
       }
       if (ctx.parentNode) {
@@ -466,21 +551,29 @@ export class QWeb extends EventBus {
         // this is an unusual situation: this text node is the result of the
         // template rendering.
         let nodeID = ctx.generateID();
-        ctx.addLine(`var vn${nodeID} = {text: \`${text}\`};`);
+        ctx.addLine(`let vn${nodeID} = {text: \`${text}\`};`);
         ctx.addLine(`result = vn${nodeID};`);
         ctx.rootContext.rootNode = nodeID;
         ctx.rootContext.parentTextNode = nodeID;
       }
       return;
     }
-    if (ctx !== ctx.rootContext) {
-      ctx = ctx.subContext("currentKey", ctx.currentKey);
+
+    if (node.tagName !== "t" && node.hasAttribute("t-call")) {
+      const tCallNode = document.implementation.createDocument(
+        "http://www.w3.org/1999/xhtml",
+        "t",
+        null
+      ).documentElement;
+      tCallNode.setAttribute("t-call", node.getAttribute("t-call")!);
+      node.removeAttribute("t-call");
+      node.prepend(tCallNode);
     }
 
     const firstLetter = node.tagName[0];
     if (firstLetter === firstLetter.toUpperCase()) {
       // this is a component, we modify in place the xml document to change
-      // <SomeComponent ... /> to <t t-component="SomeComponent" ... />
+      // <SomeComponent ... /> to <SomeComponent t-component="SomeComponent" ... />
       node.setAttribute("t-component", node.tagName);
     } else if (node.tagName !== "t" && node.hasAttribute("t-component")) {
       throw new Error(
@@ -507,7 +600,11 @@ export class QWeb extends EventBus {
           throw new Error(`Unknown QWeb directive: '${attrName}'`);
         }
         if (node.tagName !== "t" && (attrName === "t-esc" || attrName === "t-raw")) {
-          const tNode = document.createElement("t");
+          const tNode = document.implementation.createDocument(
+            "http://www.w3.org/1999/xhtml",
+            "t",
+            null
+          ).documentElement;
           tNode.setAttribute(attrName, node.getAttribute(attrName)!);
           for (let child of Array.from(node.childNodes)) {
             tNode.appendChild(child);
@@ -552,7 +649,7 @@ export class QWeb extends EventBus {
           qweb: this,
           ctx,
           fullName,
-          value
+          value,
         });
         if (isDone) {
           for (let { directive, value, fullName } of finalizers) {
@@ -563,14 +660,22 @@ export class QWeb extends EventBus {
       }
     }
 
-    if (node.nodeName !== "t") {
-      let nodeID = this._compileGenericNode(node, ctx, withHandlers);
-      ctx = ctx.withParent(nodeID);
+    if (node.nodeName !== "t" || node.hasAttribute("t-tag")) {
       let nodeHooks = {};
-      let addNodeHook = function(hook, handler) {
+      let addNodeHook = function (hook, handler) {
         nodeHooks[hook] = nodeHooks[hook] || [];
         nodeHooks[hook].push(handler);
       };
+      if (node.tagName === "select" && node.hasAttribute("t-att-value")) {
+        const value = node.getAttribute("t-att-value");
+        let exprId = ctx.generateID();
+        ctx.addLine(`let expr${exprId} = ${ctx.formatExpression(value)};`);
+        let expr = `expr${exprId}`;
+        node.setAttribute("t-att-value", expr);
+        addNodeHook("create", `n.elm.value=${expr};`);
+      }
+      let nodeID = this._compileGenericNode(node, ctx, withHandlers);
+      ctx = ctx.withParent(nodeID);
 
       for (let { directive, value, fullName } of validDirectives) {
         if (directive.atNodeCreation) {
@@ -581,7 +686,7 @@ export class QWeb extends EventBus {
             fullName,
             value,
             nodeID,
-            addNodeHook
+            addNodeHook,
           });
         }
       }
@@ -634,25 +739,36 @@ export class QWeb extends EventBus {
     const props: string[] = [];
     const tattrs: number[] = [];
 
-    function handleBooleanProps(key, val) {
+    function handleProperties(key, val) {
       let isProp = false;
-      if (node.nodeName === "input" && key === "checked") {
-        let type = (<Element>node).getAttribute("type");
-        if (type === "checkbox" || type === "radio") {
-          isProp = true;
-        }
-      }
-      if (node.nodeName === "option" && key === "selected") {
-        isProp = true;
-      }
-      if (key === "disabled" && DISABLED_TAGS.indexOf(node.nodeName) > -1) {
-        isProp = true;
-      }
-      if ((key === "readonly" && node.nodeName === "input") || node.nodeName === "textarea") {
-        isProp = true;
+      switch (node.nodeName) {
+        case "input":
+          let type = (<Element>node).getAttribute("type");
+          if (type === "checkbox" || type === "radio") {
+            if (key === "checked" || key === "indeterminate") {
+              isProp = true;
+            }
+          }
+          if (key === "value" || key === "readonly" || key === "disabled") {
+            isProp = true;
+          }
+          break;
+        case "option":
+          isProp = key === "selected" || key === "disabled";
+          break;
+        case "textarea":
+          isProp = key === "readonly" || key === "disabled" || key === "value";
+          break;
+        case "select":
+          isProp = key === "disabled" || key === "value";
+          break;
+        case "button":
+        case "optgroup":
+          isProp = key === "disabled";
+          break;
       }
       if (isProp) {
-        props.push(`${key}: _${val}`);
+        props.push(`${key}: ${val}`);
       }
     }
     let classObj = "";
@@ -672,19 +788,23 @@ export class QWeb extends EventBus {
           if ((value = value.trim())) {
             let classDef = value
               .split(/\s+/)
-              .map(a => `'${a}':true`)
+              .map((a) => `'${escapeQuotes(a)}':true`)
               .join(",");
-            classObj = `_${ctx.generateID()}`;
-            ctx.addLine(`let ${classObj} = {${classDef}};`);
+            if (classObj) {
+              ctx.addLine(`Object.assign(${classObj}, {${classDef}})`);
+            } else {
+              classObj = `_${ctx.generateID()}`;
+              ctx.addLine(`let ${classObj} = {${classDef}};`);
+            }
           }
         } else {
-          ctx.addLine(`var _${attID} = '${value}';`);
+          ctx.addLine(`let _${attID} = '${escapeQuotes(value)}';`);
           if (!name.match(/^[a-zA-Z]+$/)) {
             // attribute contains 'non letters' => we want to quote it
             name = '"' + name + '"';
           }
           attrs.push(`${name}: _${attID}`);
-          handleBooleanProps(name, attID);
+          handleProperties(name, `_${attID}`);
         }
       }
 
@@ -696,7 +816,7 @@ export class QWeb extends EventBus {
 
         if (attName === "class") {
           ctx.rootContext.shouldDefineUtils = true;
-          formattedValue = `utils.toObj(${formattedValue})`;
+          formattedValue = `utils.toClassObj(${formattedValue})`;
           if (classObj) {
             ctx.addLine(`Object.assign(${classObj}, ${formattedValue})`);
           } else {
@@ -714,14 +834,19 @@ export class QWeb extends EventBus {
           const attValue = (<Element>node).getAttribute(attName);
           if (attValue) {
             const attValueID = ctx.generateID();
-            ctx.addLine(`var _${attValueID} = ${formattedValue};`);
+            ctx.addLine(`let _${attValueID} = ${formattedValue};`);
             formattedValue = `'${attValue}' + (_${attValueID} ? ' ' + _${attValueID} : '')`;
-            const attrIndex = attrs.findIndex(att => att.startsWith(attName + ":"));
+            const attrIndex = attrs.findIndex((att) => att.startsWith(attName + ":"));
             attrs.splice(attrIndex, 1);
           }
-          ctx.addLine(`var _${attID} = ${formattedValue};`);
-          attrs.push(`${attName}: _${attID}`);
-          handleBooleanProps(attName, attID);
+          if (node.nodeName === "select" && attName === "value") {
+            attrs.push(`${attName}: ${v}`);
+            handleProperties(attName, v);
+          } else {
+            ctx.addLine(`let _${attID} = ${formattedValue};`);
+            attrs.push(`${attName}: _${attID}`);
+            handleProperties(attName, "_" + attID);
+          }
         }
       }
 
@@ -735,9 +860,9 @@ export class QWeb extends EventBus {
         const attID = ctx.generateID();
         let staticVal = (<Element>node).getAttribute(attName);
         if (staticVal) {
-          ctx.addLine(`var _${attID} = '${staticVal} ' + ${formattedExpr};`);
+          ctx.addLine(`let _${attID} = '${staticVal} ' + ${formattedExpr};`);
         } else {
-          ctx.addLine(`var _${attID} = ${formattedExpr};`);
+          ctx.addLine(`let _${attID} = ${formattedExpr};`);
         }
         attrs.push(`${attName}: _${attID}`);
       }
@@ -745,13 +870,13 @@ export class QWeb extends EventBus {
       // t-att= attributes
       if (name === "t-att") {
         let id = ctx.generateID();
-        ctx.addLine(`var _${id} = ${ctx.formatExpression(value!)};`);
+        ctx.addLine(`let _${id} = ${ctx.formatExpression(value!)};`);
         tattrs.push(id);
       }
     }
     let nodeID = ctx.generateID();
-    let nodeKey = ctx.currentKey || nodeID;
-    const parts = [`key:${nodeKey}`];
+    let key = ctx.loopNumber || ctx.hasKey0 ? `\`\${key${ctx.loopNumber}}_${nodeID}\`` : nodeID;
+    const parts = [`key:${key}`];
     if (attrs.length + tattrs.length > 0) {
       parts.push(`attrs:{${attrs.join(",")}}`);
     }
@@ -777,9 +902,19 @@ export class QWeb extends EventBus {
       ctx.addLine(`}`);
       ctx.closeIf();
     }
-    ctx.addLine(`var vn${nodeID} = h('${node.nodeName}', p${nodeID}, c${nodeID});`);
+    let nodeName = `'${node.nodeName}'`;
+    if ((<Element>node).hasAttribute("t-tag")) {
+      const tagExpr = (<Element>node).getAttribute("t-tag");
+      (<Element>node).removeAttribute("t-tag");
+      nodeName = `tag${ctx.generateID()}`;
+      ctx.addLine(`let ${nodeName} = ${ctx.formatExpression(tagExpr)};`);
+    }
+    ctx.addLine(`let vn${nodeID} = h(${nodeName}, p${nodeID}, c${nodeID});`);
     if (ctx.parentNode) {
       ctx.addLine(`c${ctx.parentNode}.push(vn${nodeID});`);
+    } else if (ctx.loopNumber || ctx.hasKey0) {
+      ctx.rootContext.shouldDefineResult = true;
+      ctx.addLine(`result = vn${nodeID};`);
     }
 
     return nodeID;

src/router/link.ts

@@ -4,7 +4,7 @@ import { Destination, RouterEnv } from "./router";
 
 type Props = Destination;
 
-export class Link<Env extends RouterEnv> extends Component<Env, Props> {
+export class Link<Env extends RouterEnv> extends Component<Props, Env> {
   static template = xml`
     <a  t-att-class="{'router-link-active': isActive }"
         t-att-href="href"

src/router/route_component.ts

@@ -1,7 +1,8 @@
 import { Component } from "../component/component";
 import { xml } from "../tags";
+import { EnvWithRouter } from "./router";
 
-export class RouteComponent extends Component<any, {}> {
+export class RouteComponent extends Component<{}, EnvWithRouter> {
   static template = xml`
     <t>
         <t

src/router/router.ts

@@ -11,6 +11,7 @@ type NavigationGuard = (info: {
 export interface Route {
   name: string;
   path: string;
+  extractionRegExp: RegExp;
   component?: any;
   redirect?: Destination;
   params: string[];
@@ -49,7 +50,12 @@ interface Options {
   mode: Router["mode"];
 }
 
+export interface EnvWithRouter extends Env {
+  router: Router;
+}
+
 const paramRegexp = /\{\{(.*?)\}\}/;
+const globalParamRegexp = new RegExp(paramRegexp.source, "g");
 
 export class Router {
   currentRoute: Route | null = null;
@@ -60,7 +66,11 @@ export class Router {
   routeIds: string[];
   env: RouterEnv;
 
-  constructor(env: Env, routes: Partial<Route>[], options: Options = { mode: "history" }) {
+  constructor(
+    env: Partial<EnvWithRouter>,
+    routes: Partial<Route>[],
+    options: Options = { mode: "history" }
+  ) {
     env.router = this;
     this.mode = options.mode;
     this.env = env as RouterEnv;
@@ -79,6 +89,7 @@ export class Router {
         this.validateDestination(partialRoute.redirect);
       }
       partialRoute.params = partialRoute.path ? findParams(partialRoute.path) : [];
+      partialRoute.extractionRegExp = makeExtractionRegExp(partialRoute.path);
       this.routes[partialRoute.name] = partialRoute as Route;
       this.routeIds.push(partialRoute.name);
     }
@@ -89,7 +100,7 @@ export class Router {
   //--------------------------------------------------------------------------
 
   async start() {
-    (this as any)._listener = ev => this._navigate(this.currentPath(), ev);
+    (this as any)._listener = (ev) => this._navigate(this.currentPath(), ev);
     window.addEventListener("popstate", (this as any)._listener);
     if (this.mode === "hash") {
       window.addEventListener("hashchange", (this as any)._listener);
@@ -114,7 +125,10 @@ export class Router {
     const initialParams = this.currentParams;
     const result = await this.matchAndApplyRules(path);
     if (result.type === "match") {
-      const finalPath = this.routeToPath(result.route, result.params);
+      let finalPath = this.routeToPath(result.route, result.params);
+      if (path.indexOf("?") > -1) {
+        finalPath += "?" + path.split("?")[1];
+      }
       const isPopStateEvent = ev && ev instanceof PopStateEvent;
       if (!isPopStateEvent) {
         this.setUrlFromPath(finalPath);
@@ -162,19 +176,14 @@ export class Router {
   }
 
   private routeToPath(route: Route, params: RouteParams): string {
-    const path = route.path;
-    const parts = path.split("/");
-    const l = parts.length;
-    for (let i = 0; i < l; i++) {
-      const part = parts[i];
-      const match = part.match(paramRegexp);
-      if (match) {
-        const key = match[1].split(".")[0];
-        parts[i] = <string>params[key];
-      }
-    }
     const prefix = this.mode === "hash" ? "#" : "";
-    return prefix + parts.join("/");
+    return (
+      prefix +
+      route.path.replace(globalParamRegexp, (match, param) => {
+        const [key] = param.split(".");
+        return <string>params[key];
+      })
+    );
   }
 
   private currentPath(): string {
@@ -190,7 +199,7 @@ export class Router {
         return {
           type: "match",
           route: route,
-          params: params
+          params: params,
         };
       }
     }
@@ -215,7 +224,7 @@ export class Router {
       const result = await route.beforeRouteEnter({
         env: this.env,
         from: this.currentRoute,
-        to: route
+        to: route,
       });
       if (result === false) {
         return { type: "cancelled" };
@@ -233,43 +242,53 @@ export class Router {
     if (route.path === "*") {
       return {};
     }
+    if (path.indexOf("?") > -1) {
+      path = path.split("?")[0];
+    }
     if (path.startsWith("#")) {
       path = path.slice(1);
     }
-    const descrParts = route.path.split("/");
-    const targetParts = path.split("/");
-    const l = descrParts.length;
-    if (l !== targetParts.length) {
+    const paramsMatch = path.match(route.extractionRegExp);
+    if (!paramsMatch) {
       return false;
     }
     const result = {};
-    for (let i = 0; i < l; i++) {
-      const descr = descrParts[i];
-      let target: string | number = targetParts[i];
-      const match = descr.match(paramRegexp);
-      if (match) {
-        const [key, suffix] = match[1].split(".");
-        if (suffix === "number") {
-          target = parseInt(target, 10);
-        }
-        result[key] = target;
-      } else if (descr !== target) {
-        return false;
+    route.params.forEach((param, index) => {
+      const [key, suffix] = param.split(".");
+      const paramValue = paramsMatch[index + 1];
+      if (suffix === "number") {
+        return (result[key] = parseInt(paramValue, 10));
       }
-    }
+      return (result[key] = paramValue);
+    });
     return result;
   }
 }
 
 function findParams(str: string): string[] {
-  const globalParamRegexp = /\{\{(.*?)\}\}/g;
   const result: string[] = [];
   let m;
   do {
     m = globalParamRegexp.exec(str);
     if (m) {
-      result.push(m[1].split(".")[0]);
+      result.push(m[1]);
     }
   } while (m);
   return result;
 }
+
+function escapeRegExp(str: string) {
+  return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
+}
+
+function makeExtractionRegExp(path: string) {
+  // replace param strings with capture groups so that we can build a regex to match over the path
+  const extractionString = path
+    .split(paramRegexp)
+    .map((part, index) => {
+      return index % 2 ? "(.*)" : escapeRegExp(part);
+    })
+    .join("");
+  // Example: /home/{{param1}}/{{param2}} => ^\/home\/(.*)\/(.*)$
+  return new RegExp(`^${extractionString}$`);
+}

src/store.ts

@@ -1,5 +1,4 @@
-import { Component } from "./component/component";
-import { Env } from "./component/component";
+import { Component, Env } from "./component/component";
 import { Context, useContextWithCB } from "./context";
 import { onWillUpdateProps } from "./hooks";
 
@@ -24,6 +23,10 @@ import { onWillUpdateProps } from "./hooks";
 // Store Definition
 //------------------------------------------------------------------------------
 
+export interface EnvWithStore extends Env {
+  store: Store;
+}
+
 export type Action = ({ state, dispatch, env, getters }, ...payload: any) => any;
 export type Getter = ({ state: any, getters }, payload?) => any;
 
@@ -49,7 +52,7 @@ export class Store extends Context {
     if (config.getters) {
       const firstArg = {
         state: this.state,
-        getters: this.getters
+        getters: this.getters,
       };
       for (let g in config.getters) {
         this.getters[g] = config.getters[g].bind(this, firstArg);
@@ -66,12 +69,17 @@ export class Store extends Context {
         dispatch: this.dispatch.bind(this),
         env: this.env,
         state: this.state,
-        getters: this.getters
+        getters: this.getters,
       },
       ...payload
     );
     return result;
   }
+
+  __notifyComponents(): Promise<void> {
+    this.trigger("before-update");
+    return super.__notifyComponents();
+  }
 }
 
 interface SelectorOptions {
@@ -83,7 +91,7 @@ interface SelectorOptions {
 const isStrictEqual = (a, b) => a === b;
 
 export function useStore(selector, options: SelectorOptions = {}): any {
-  const component: Component<any, any> = Component.current!;
+  const component = Component.current as Component<any, EnvWithStore>;
   const componentId = component.__owl__.id;
   const store = options.store || (component.env.store as Store);
   if (!(store instanceof Store)) {
@@ -102,18 +110,21 @@ export function useStore(selector, options: SelectorOptions = {}): any {
     const newRevNumber = hashFn(result);
     if ((newRevNumber > 0 && revNumber !== newRevNumber) || !isEqual(oldResult, result)) {
       revNumber = newRevNumber;
-      if (options.onUpdate) {
-        options.onUpdate(result);
-      }
       return true;
     }
     return false;
   }
-  store.updateFunctions[componentId].push(function(): boolean {
+  if (options.onUpdate) {
+    store.on("before-update", component, () => {
+      const newValue = selector(store!.state, component.props!);
+      options.onUpdate(newValue);
+    });
+  }
+  store.updateFunctions[componentId].push(function (): boolean {
     return selectCompareUpdate(store!.state, component.props);
   });
 
-  useContextWithCB(store, component, function(): Promise<void> | void {
+  useContextWithCB(store, component, function (): Promise<void> | void {
     let shouldRender = false;
     for (let fn of store.updateFunctions[componentId]) {
       shouldRender = fn() || shouldRender;
@@ -122,17 +133,20 @@ export function useStore(selector, options: SelectorOptions = {}): any {
       return component.render();
     }
   });
-  onWillUpdateProps(props => {
+  onWillUpdateProps((props) => {
     selectCompareUpdate(store.state, props);
   });
 
   const __destroy = component.__destroy;
-  component.__destroy = parent => {
+  component.__destroy = (parent) => {
     delete store.updateFunctions[componentId];
+    if (options.onUpdate) {
+      store.off("before-update", component);
+    }
     __destroy.call(component, parent);
   };
 
-  if (typeof result !== "object") {
+  if (typeof result !== "object" || result === null) {
     return result;
   }
   return new Proxy(result, {
@@ -141,16 +155,19 @@ export function useStore(selector, options: SelectorOptions = {}): any {
     },
     set(target, k, v) {
       throw new Error("Store state should only be modified through actions");
-    }
+    },
+    has(target, k) {
+      return k in result;
+    },
   });
 }
 
 export function useDispatch(store?: Store): Store["dispatch"] {
-  store = store || (Component.current!.env.store as Store);
+  store = store || (Component.current!.env as EnvWithStore).store;
   return store.dispatch.bind(store);
 }
 
 export function useGetters(store?: Store): Store["getters"] {
-  store = store || (Component.current!.env.store as Store);
+  store = store || (Component.current!.env as EnvWithStore).store;
   return store.getters;
 }

src/tags.ts

@@ -1,4 +1,5 @@
 import { QWeb } from "./qweb/index";
+import { registerSheet } from "./component/styles";
 
 /**
  * Owl Tags
@@ -25,3 +26,19 @@ export function xml(strings, ...args) {
   QWeb.registerTemplate(name, value);
   return name;
 }
+
+/**
+ * CSS tag helper for defining inline stylesheets.  With this, one can simply define
+ * an inline stylesheet with just the following code:
+ * ```js
+ *   class A extends Component {
+ *     static style = css`.component-a { color: red; }`;
+ *   }
+ * ```
+ */
+export function css(strings, ...args) {
+  const name = `__sheet__${QWeb.nextId++}`;
+  const value = String.raw(strings, ...args);
+  registerSheet(name, value);
+  return name;
+}

src/utils.ts

@@ -10,14 +10,16 @@
  * - debounce
  */
 
+import { browser } from "./browser";
+
 export function whenReady(fn?: any) {
-  return new Promise(function(resolve) {
+  return new Promise(function (resolve) {
     if (document.readyState !== "loading") {
       resolve();
     } else {
       document.addEventListener("DOMContentLoaded", resolve, false);
     }
-  }).then(fn || function() {});
+  }).then(fn || function () {});
 }
 
 const loadedScripts: { [key: string]: Promise<void> } = {};
@@ -26,14 +28,14 @@ export function loadJS(url: string): Promise<void> {
   if (url in loadedScripts) {
     return loadedScripts[url];
   }
-  const promise: Promise<void> = new Promise(function(resolve, reject) {
+  const promise: Promise<void> = new Promise(function (resolve, reject) {
     const script = document.createElement("script");
     script.type = "text/javascript";
     script.src = url;
-    script.onload = function() {
+    script.onload = function () {
       resolve();
     };
-    script.onerror = function() {
+    script.onerror = function () {
       reject(`Error loading file '${url}'`);
     };
     const head = document.head || document.getElementsByTagName("head")[0];
@@ -44,7 +46,7 @@ export function loadJS(url: string): Promise<void> {
 }
 
 export async function loadFile(url: string): Promise<string> {
-  const result = await fetch(url);
+  const result = await browser.fetch(url);
   if (!result.ok) {
     throw new Error("Error while fetching xml templates");
   }
@@ -73,7 +75,7 @@ export function escape(str: string | number | undefined): string {
  */
 export function debounce(func: Function, wait: number, immediate?: boolean): Function {
   let timeout;
-  return function(this: any) {
+  return function (this: any) {
     const context = this;
     const args = arguments;
     function later() {
@@ -83,8 +85,8 @@ export function debounce(func: Function, wait: number, immediate?: boolean): Fun
       }
     }
     const callNow = immediate && !timeout;
-    clearTimeout(timeout);
-    timeout = setTimeout(later, wait);
+    browser.clearTimeout(timeout);
+    timeout = browser.setTimeout(later, wait);
     if (callNow) {
       func.apply(context, args);
     }

src/vdom/html_to_vdom.ts

@@ -1,4 +1,4 @@
-import { VNode, h } from "./vdom";
+import { VNode, h, addNS } from "./vdom";
 
 const parser = new DOMParser();
 
@@ -13,6 +13,9 @@ export function htmlToVDOM(html: string): VNode[] {
 
 function htmlToVNode(node: ChildNode): VNode {
   if (!(node instanceof Element)) {
+    if (node instanceof Comment) {
+      return h("!", node.textContent);
+    }
     return { text: node.textContent! } as VNode;
   }
   const attrs = {};
@@ -23,5 +26,9 @@ function htmlToVNode(node: ChildNode): VNode {
   for (let c of node.childNodes) {
     children.push(htmlToVNode(c));
   }
-  return h((node as Element).tagName, { attrs }, children);
+  const vnode = h((node as Element).tagName, { attrs }, children);
+  if (vnode.sel === "svg") {
+    addNS(vnode.data, (vnode as any).children, vnode.sel);
+  }
+  return vnode;
 }

src/vdom/modules.ts

@@ -33,7 +33,7 @@ function updateProps(oldVnode: VNode, vnode: VNode): void {
 
 export const propsModule = {
   create: updateProps,
-  update: updateProps
+  update: updateProps,
 } as Module;
 
 //------------------------------------------------------------------------------
@@ -70,8 +70,12 @@ function handleEvent(event: Event, vnode: VNode) {
     on = (vnode.data as VNodeData).on;
 
   // call event handler(s) if exists
-  if (on && on[name]) {
-    invokeHandler(on[name], vnode, event);
+  if (on) {
+    if (on[name]) {
+      invokeHandler(on[name], vnode, event);
+    } else if (on["!" + name]) {
+      invokeHandler(on["!" + name], vnode, event);
+    }
   }
 }
 
@@ -100,13 +104,17 @@ function updateEventListeners(oldVnode: VNode, vnode?: VNode): void {
     if (!on) {
       for (name in oldOn) {
         // remove listener if element was changed or existing listeners removed
-        oldElm.removeEventListener(name, oldListener, false);
+        const capture = name.charAt(0) === "!";
+        name = capture ? name.slice(1) : name;
+        oldElm.removeEventListener(name, oldListener, capture);
       }
     } else {
       for (name in oldOn) {
         // remove listener if existing listener removed
         if (!on[name]) {
-          oldElm.removeEventListener(name, oldListener, false);
+          const capture = name.charAt(0) === "!";
+          name = capture ? name.slice(1) : name;
+          oldElm.removeEventListener(name, oldListener, capture);
         }
       }
     }
@@ -123,13 +131,17 @@ function updateEventListeners(oldVnode: VNode, vnode?: VNode): void {
     if (!oldOn) {
       for (name in on) {
         // add listener if element was changed or new listeners added
-        elm.addEventListener(name, listener, false);
+        const capture = name.charAt(0) === "!";
+        name = capture ? name.slice(1) : name;
+        elm.addEventListener(name, listener, capture);
       }
     } else {
       for (name in on) {
         // add listener if new listener added
         if (!oldOn[name]) {
-          elm.addEventListener(name, listener, false);
+          const capture = name.charAt(0) === "!";
+          name = capture ? name.slice(1) : name;
+          elm.addEventListener(name, listener, capture);
         }
       }
     }
@@ -139,7 +151,7 @@ function updateEventListeners(oldVnode: VNode, vnode?: VNode): void {
 export const eventListenersModule = {
   create: updateEventListeners,
   update: updateEventListeners,
-  destroy: updateEventListeners
+  destroy: updateEventListeners,
 } as Module;
 
 //------------------------------------------------------------------------------
@@ -198,7 +210,7 @@ function updateAttrs(oldVnode: VNode, vnode: VNode): void {
 
 export const attrsModule = {
   create: updateAttrs,
-  update: updateAttrs
+  update: updateAttrs,
 } as Module;
 
 //------------------------------------------------------------------------------
@@ -219,7 +231,8 @@ function updateClass(oldVnode: VNode, vnode: VNode): void {
   elm = vnode.elm as Element;
 
   for (name in oldClass) {
-    if (name && !klass[name]) {
+    if (name && !klass[name] && !Object.prototype.hasOwnProperty.call(klass, name)) {
+      // was `true` and now not provided
       elm.classList.remove(name);
     }
   }

src/vdom/vdom.ts

@@ -520,7 +520,7 @@ const htmlDomApi = {
   parentNode,
   nextSibling,
   tagName,
-  setTextContent
+  setTextContent,
 } as DOMAPI;
 
 //------------------------------------------------------------------------------

tests/__snapshots__/animations.test.ts.snap

@@ -8,9 +8,9 @@ exports[`animations t-transition combined with component 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     // Component 'Child'
     let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
     let props2 = {};
@@ -24,11 +24,11 @@ exports[`animations t-transition combined with component 1`] = `
         c1.push(pvnode);
     } else {
         let componentKey2 = \`Child\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
+        let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
         if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
         w2 = new W2(parent, props2);
         const __patch2 = w2.__patch;
-        w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
+        w2.__patch = (t, vn) => {__patch2.call(w2, t, vn); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
         parent.__owl__.cmap['__3__'] = w2.__owl__.id;
         let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {let finalize = () => {
@@ -52,9 +52,9 @@ exports[`animations t-transition combined with t-component and t-if 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     if (scope['state'].display) {
         // Component 'Child'
         let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
@@ -69,11 +69,11 @@ exports[`animations t-transition combined with t-component and t-if 1`] = `
             c1.push(pvnode);
         } else {
             let componentKey2 = \`Child\`;
-            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
+            let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
             if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
             w2 = new W2(parent, props2);
             const __patch2 = w2.__patch;
-            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
+            w2.__patch = (t, vn) => {__patch2.call(w2, t, vn); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
             parent.__owl__.cmap['__3__'] = w2.__owl__.id;
             let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
             let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {let finalize = () => {
@@ -98,9 +98,9 @@ exports[`animations t-transition combined with t-component, remove and re-add be
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     if (scope['state'].flag) {
         // Component 'Child'
         let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
@@ -115,11 +115,11 @@ exports[`animations t-transition combined with t-component, remove and re-add be
             c1.push(pvnode);
         } else {
             let componentKey2 = \`Child\`;
-            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
+            let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
             if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
             w2 = new W2(parent, props2);
             const __patch2 = w2.__patch;
-            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
+            w2.__patch = (t, vn) => {__patch2.call(w2, t, vn); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
             parent.__owl__.cmap['__3__'] = w2.__owl__.id;
             let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
             let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {let finalize = () => {
@@ -141,9 +141,9 @@ exports[`animations t-transition with no delay/duration 1`] = `
 ) {
     // Template name: \\"test\\"
     let utils = this.constructor.utils;
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('span', p1, c1);
+    let vn1 = h('span', p1, c1);
     p1.hook = {
       insert: vn => {
         utils.transitionInsert(vn, 'jupiler');
@@ -162,9 +162,30 @@ exports[`animations t-transition, on a simple node (insert) 1`] = `
 ) {
     // Template name: \\"test\\"
     let utils = this.constructor.utils;
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('span', p1, c1);
+    let vn1 = h('span', p1, c1);
+    p1.hook = {
+      insert: vn => {
+        utils.transitionInsert(vn, 'chimay');
+      },
+      remove: (vn, rm) => {
+        utils.transitionRemove(vn, 'chimay', rm);
+      },
+    };
+    c1.push({text: \`blue\`});
+    return vn1;
+}"
+`;
+
+exports[`animations t-transition, on a simple node, not in the DOM 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('span', p1, c1);
     p1.hook = {
       insert: vn => {
         utils.transitionInsert(vn, 'chimay');

tests/animations.test.ts

@@ -1,15 +1,15 @@
 import { Component, Env } from "../src/component/component";
+import { useRef, useState } from "../src/hooks";
 import { QWeb } from "../src/qweb/index";
-import { useState, useRef } from "../src/hooks";
 import { xml } from "../src/tags";
 import {
   makeDeferred,
-  makeTestFixture,
   makeTestEnv,
+  makeTestFixture,
+  nextFrame,
   patchNextFrame,
   renderToDOM,
   unpatchNextFrame,
-  nextTick
 } from "./helpers";
 
 //------------------------------------------------------------------------------
@@ -71,7 +71,27 @@ describe("animations", () => {
     qweb.addTemplate("test", `<span t-transition="chimay">blue</span>`);
 
     let def = makeDeferred();
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
+      expect(node.className).toBe("chimay-enter chimay-enter-active");
+      cb();
+      expect(node.className).toBe("chimay-enter-active chimay-enter-to");
+      def.resolve();
+    });
+    let node: HTMLElement = <HTMLElement>renderToDOM(qweb, "test");
+    fixture.appendChild(node);
+
+    expect(node.className).toBe("chimay-enter chimay-enter-active");
+    await def; // wait for the mocked repaint to be done
+    node.dispatchEvent(new Event("transitionend")); // mock end of css transition
+    expect(node.className).toBe("");
+  });
+
+  test("t-transition, on a simple node, not in the DOM", async () => {
+    expect.assertions(5);
+    qweb.addTemplate("test", `<span t-transition="chimay">blue</span>`);
+
+    let def = makeDeferred();
+    patchNextFrame((cb) => {
       expect(node.className).toBe("chimay-enter chimay-enter-active");
       cb();
       expect(node.className).toBe("chimay-enter-active chimay-enter-to");
@@ -81,8 +101,10 @@ describe("animations", () => {
 
     expect(node.className).toBe("chimay-enter chimay-enter-active");
     await def; // wait for the mocked repaint to be done
-    node.dispatchEvent(new Event("transitionend")); // mock end of css transition
-    expect(node.className).toBe("");
+    node.dispatchEvent(new Event("transitionend"));
+    // we check here that the css classes have not been removed, since the
+    // element is not in the dom, we actually do not want to do anything.
+    expect(node.className).toBe("chimay-enter-active chimay-enter-to");
   });
 
   test("t-transition with no delay/duration", async () => {
@@ -90,13 +112,14 @@ describe("animations", () => {
     qweb.addTemplate("test", `<span t-transition="jupiler">blue</span>`);
 
     let def = makeDeferred();
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(node.className).toBe("jupiler-enter jupiler-enter-active");
       cb();
       expect(node.className).toBe("");
       def.resolve();
     });
     let node: HTMLElement = <HTMLElement>renderToDOM(qweb, "test");
+    fixture.appendChild(node);
     expect(node.className).toBe("jupiler-enter jupiler-enter-active");
     await def;
   });
@@ -116,7 +139,7 @@ describe("animations", () => {
     // insert widget into the DOM
     let def = makeDeferred();
     var spanNode;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(spanNode.className).toBe("chimay-enter chimay-enter-active");
       cb();
       expect(spanNode.className).toBe("chimay-enter-active chimay-enter-to");
@@ -132,7 +155,7 @@ describe("animations", () => {
     // remove span from the DOM
     def = makeDeferred();
     widget.state.hide = true;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(spanNode.className).toBe("chimay-leave chimay-leave-active");
       cb();
       expect(spanNode.className).toBe("chimay-leave-active chimay-leave-to");
@@ -159,7 +182,7 @@ describe("animations", () => {
     // insert widget into the DOM
     let def = makeDeferred();
     var spanNode;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(spanNode.className).toBe("chimay-enter chimay-enter-active");
       cb();
       expect(spanNode.className).toBe("chimay-enter-active chimay-enter-to");
@@ -187,7 +210,7 @@ describe("animations", () => {
 
     let def = makeDeferred();
     var spanNode;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(fixture.innerHTML).toBe(
         '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
       );
@@ -227,7 +250,7 @@ describe("animations", () => {
 
     let def = makeDeferred();
     var spanNode;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(fixture.innerHTML).toBe(
         '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
       );
@@ -252,7 +275,7 @@ describe("animations", () => {
     // remove span from the DOM
     def = makeDeferred();
     widget.state.display = false;
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       expect(fixture.innerHTML).toBe(
         '<div><span class="chimay-leave chimay-leave-active" data-owl-key="__3__">blue</span></div>'
       );
@@ -292,7 +315,7 @@ describe("animations", () => {
 
     let def = makeDeferred();
     let phase = "enter";
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       let spans = fixture.querySelectorAll("span");
       expect(spans.length).toBe(1);
       expect(spans[0].className).toBe(`chimay-${phase} chimay-${phase}-active`);
@@ -343,7 +366,7 @@ describe("animations", () => {
 
     let def = makeDeferred();
     let phase = "enter";
-    patchNextFrame(cb => {
+    patchNextFrame((cb) => {
       let spans = fixture.querySelectorAll("span");
       expect(spans.length).toBe(1);
       expect(spans[0].className).toBe(`chimay-${phase} chimay-${phase}-active`);
@@ -390,36 +413,36 @@ describe("animations", () => {
       state = useState({ flag: false });
     }
 
-    patchNextFrame(cb => cb());
+    patchNextFrame((cb) => cb());
 
     const widget = new Parent();
     await widget.mount(fixture);
 
     widget.state.flag = true;
 
-    await nextTick();
+    await nextFrame();
     widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend"));
     expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(1);
 
     widget.state.flag = false;
-    await nextTick();
+    await nextFrame();
     expect(fixture.innerHTML).toBe(
       '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__3__">blue</span></div>'
     );
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(1);
 
     widget.state.flag = true;
-    await nextTick();
+    await nextFrame();
     expect(fixture.innerHTML).toBe(
       '<div><span class="chimay-enter-active chimay-enter-to" data-owl-key="__3__">blue</span></div>'
     );
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(2);
 
     widget.state.flag = false;
-    await nextTick();
+    await nextFrame();
     widget.state.flag = true;
-    await nextTick();
+    await nextFrame();
 
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(3);
     widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend"));

tests/component/__snapshots__/class_style.test.ts.snap

@@ -0,0 +1,156 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`class and style attributes with t-component dynamic t-att-style is properly added and updated on widget root el 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"ParentWidget\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    // Component 'child'
+    const _4 = scope['state'].style;
+    let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
+    let props2 = {};
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
+        w2.destroy();
+        w2 = false;
+    }
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, undefined).then(()=>{if (w2.__owl__.status === 5) {return};w2.el.style=_4;});;
+        let pvnode = w2.__owl__.pvnode;
+        c1.push(pvnode);
+    } else {
+        let componentKey2 = \`child\`;
+        let W2 = scope['child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
+        w2 = new W2(parent, props2);
+        parent.__owl__.cmap['__3__'] = w2.__owl__.id;
+        let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; utils.assignHooks(vnode.data, {create(_, vn){vn.elm.style = _4;}});});
+        let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {w2.destroy();}}});
+        c1.push(pvnode);
+        w2.__owl__.pvnode = pvnode;
+    }
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    return vn1;
+}"
+`;
+
+exports[`class and style attributes with t-component t-att-class is properly added/removed on widget root el (v2) 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"ParentWidget\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    context.__owl__.refs = context.__owl__.refs || {};
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    // Component 'Child'
+    const ref4 = \`child\`;
+    let _5 = {'a':true};
+    Object.assign(_5, {b:scope['state'].b})
+    let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
+    let props2 = {};
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
+        w2.destroy();
+        w2 = false;
+    }
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, undefined);
+        let pvnode = w2.__owl__.pvnode;
+        c1.push(pvnode);
+    } else {
+        let componentKey2 = \`Child\`;
+        let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
+        w2 = new W2(parent, props2);
+        parent.__owl__.cmap['__3__'] = w2.__owl__.id;
+        let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; utils.assignHooks(vnode.data, {create(_, vn){}});});
+        let pvnode = h('dummy', {key: '__3__', hook: {insert(vn) {context.__owl__.refs[ref4] = w2;},remove() {},destroy(vn) {w2.destroy();delete context.__owl__.refs[ref4];}}});
+        c1.push(pvnode);
+        w2.__owl__.pvnode = pvnode;
+    }
+    w2.__owl__.classObj=_5;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    return vn1;
+}"
+`;
+
+exports[`class and style attributes with t-component t-att-class is properly added/removed on widget root el (v2) 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"Child\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _7 = {'c':true};
+    Object.assign(_7, utils.toClassObj({d:scope['state'].d}))
+    let c8 = [], p8 = {key:8,class:_7};
+    let vn8 = h('span', p8, c8);
+    return vn8;
+}"
+`;
+
+exports[`class and style attributes with t-component t-att-class is properly added/removed on widget root el (v3) 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"ParentWidget\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    context.__owl__.refs = context.__owl__.refs || {};
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    // Component 'Child'
+    const ref4 = \`child\`;
+    let _5 = {'a':true};
+    Object.assign(_5, utils.toClassObj(scope['state'].b?'b':''))
+    let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
+    let props2 = {};
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
+        w2.destroy();
+        w2 = false;
+    }
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, undefined);
+        let pvnode = w2.__owl__.pvnode;
+        c1.push(pvnode);
+    } else {
+        let componentKey2 = \`Child\`;
+        let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
+        w2 = new W2(parent, props2);
+        parent.__owl__.cmap['__3__'] = w2.__owl__.id;
+        let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; utils.assignHooks(vnode.data, {create(_, vn){}});});
+        let pvnode = h('dummy', {key: '__3__', hook: {insert(vn) {context.__owl__.refs[ref4] = w2;},remove() {},destroy(vn) {w2.destroy();delete context.__owl__.refs[ref4];}}});
+        c1.push(pvnode);
+        w2.__owl__.pvnode = pvnode;
+    }
+    w2.__owl__.classObj=_5;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    return vn1;
+}"
+`;
+
+exports[`class and style attributes with t-component t-att-class is properly added/removed on widget root el (v3) 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"Child\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _7 = {'c':true};
+    Object.assign(_7, utils.toClassObj(scope['state'].d?'d':''))
+    let c8 = [], p8 = {key:8,class:_7};
+    let vn8 = h('span', p8, c8);
+    return vn8;
+}"
+`;

tests/component/__snapshots__/props_validation.test.ts.snap

@@ -8,9 +8,9 @@ exports[`props validation props are validated in dev mode (code snapshot) 1`] =
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     // Component 'Child'
     let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
     let props2 = {message:1};
@@ -24,7 +24,7 @@ exports[`props validation props are validated in dev mode (code snapshot) 1`] =
         c1.push(pvnode);
     } else {
         let componentKey2 = \`Child\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
+        let W2 = scope['Child'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
         if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
         w2 = new W2(parent, props2);
         parent.__owl__.cmap['__3__'] = w2.__owl__.id;

tests/component/__snapshots__/slots.test.ts.snap

@@ -8,9 +8,9 @@ exports[`t-slot directive can define and call slots 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     // Component 'Dialog'
     let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
     let props2 = {};
@@ -19,17 +19,17 @@ exports[`t-slot directive can define and call slots 1`] = `
         w2 = false;
     }
     if (w2) {
-        w2.__updateProps(props2, extra.fiber, Object.assign(Object.create(context), scope));
+        w2.__updateProps(props2, extra.fiber, utils.combine(context, scope));
         let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
         let componentKey2 = \`Dialog\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Dialog'];
+        let W2 = scope['Dialog'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
         if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
         w2 = new W2(parent, props2);
         parent.__owl__.cmap['__3__'] = w2.__owl__.id;
         w2.__owl__.slotId = 1;
-        let fiber = w2.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        let fiber = w2.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {w2.destroy();}}});
         c1.push(pvnode);
         w2.__owl__.pvnode = pvnode;
@@ -43,24 +43,24 @@ exports[`t-slot directive can define and call slots 2`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"Dialog\\"
-    var h = this.h;
-    let c6 = [], p6 = {key:6};
-    var vn6 = h('div', p6, c6);
-    let c7 = [], p7 = {key:7};
-    var vn7 = h('div', p7, c7);
-    c6.push(vn7);
-    const slot8 = this.constructor.slots[context.__owl__.slotId + '_' + 'header'];
-    if (slot8) {
-        slot8.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c7, parent: extra.parent || context}));
-    }
+    let h = this.h;
+    let c8 = [], p8 = {key:8};
+    let vn8 = h('div', p8, c8);
     let c9 = [], p9 = {key:9};
-    var vn9 = h('div', p9, c9);
-    c6.push(vn9);
-    const slot10 = this.constructor.slots[context.__owl__.slotId + '_' + 'footer'];
+    let vn9 = h('div', p9, c9);
+    c8.push(vn9);
+    const slot10 = this.constructor.slots[context.__owl__.slotId + '_' + 'header'];
     if (slot10) {
         slot10.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c9, parent: extra.parent || context}));
     }
-    return vn6;
+    let c11 = [], p11 = {key:11};
+    let vn11 = h('div', p11, c11);
+    c8.push(vn11);
+    const slot12 = this.constructor.slots[context.__owl__.slotId + '_' + 'footer'];
+    if (slot12) {
+        slot12.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c11, parent: extra.parent || context}));
+    }
+    return vn8;
 }"
 `;
 
@@ -68,12 +68,13 @@ exports[`t-slot directive can define and call slots 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_header_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
-    c1.push(vn4);
-    c4.push({text: \`header\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
+    let c5 = [], p5 = {key:5};
+    let vn5 = h('span', p5, c5);
+    c4.push(vn5);
+    c5.push({text: \`header\`});
 }"
 `;
 
@@ -81,12 +82,105 @@ exports[`t-slot directive can define and call slots 4`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_footer_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
+    let parent = extra.parent;
+    let h = this.h;
+    let c6 = extra.parentNode;
+    let c7 = [], p7 = {key:7};
+    let vn7 = h('span', p7, c7);
+    c6.push(vn7);
+    c7.push({text: \`footer\`});
+}"
+`;
+
+exports[`t-slot directive can define and call slots using old t-set keyword 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__2\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    // Component 'Dialog'
+    let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
+    let props2 = {};
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
+        w2.destroy();
+        w2 = false;
+    }
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, utils.combine(context, scope));
+        let pvnode = w2.__owl__.pvnode;
+        c1.push(pvnode);
+    } else {
+        let componentKey2 = \`Dialog\`;
+        let W2 = scope['Dialog'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
+        w2 = new W2(parent, props2);
+        parent.__owl__.cmap['__3__'] = w2.__owl__.id;
+        w2.__owl__.slotId = 1;
+        let fiber = w2.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {w2.destroy();}}});
+        c1.push(pvnode);
+        w2.__owl__.pvnode = pvnode;
+    }
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    return vn1;
+}"
+`;
+
+exports[`t-slot directive can define and call slots using old t-set keyword 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__1\\"
+    let h = this.h;
+    let c8 = [], p8 = {key:8};
+    let vn8 = h('div', p8, c8);
+    let c9 = [], p9 = {key:9};
+    let vn9 = h('div', p9, c9);
+    c8.push(vn9);
+    const slot10 = this.constructor.slots[context.__owl__.slotId + '_' + 'header'];
+    if (slot10) {
+        slot10.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c9, parent: extra.parent || context}));
+    }
+    let c11 = [], p11 = {key:11};
+    let vn11 = h('div', p11, c11);
+    c8.push(vn11);
+    const slot12 = this.constructor.slots[context.__owl__.slotId + '_' + 'footer'];
+    if (slot12) {
+        slot12.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c11, parent: extra.parent || context}));
+    }
+    return vn8;
+}"
+`;
+
+exports[`t-slot directive can define and call slots using old t-set keyword 3`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"slot_header_template\\"
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
-    var vn5 = h('span', p5, c5);
-    c1.push(vn5);
-    c5.push({text: \`footer\`});
+    let vn5 = h('span', p5, c5);
+    c4.push(vn5);
+    c5.push({text: \`header\`});
+}"
+`;
+
+exports[`t-slot directive can define and call slots using old t-set keyword 4`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"slot_footer_template\\"
+    let parent = extra.parent;
+    let h = this.h;
+    let c6 = extra.parentNode;
+    let c7 = [], p7 = {key:7};
+    let vn7 = h('span', p7, c7);
+    c6.push(vn7);
+    c7.push({text: \`footer\`});
 }"
 `;
 
@@ -94,12 +188,13 @@ exports[`t-slot directive content is the default slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
-    c1.push(vn4);
-    c4.push({text: \`sts rocks\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
+    let c5 = [], p5 = {key:5};
+    let vn5 = h('span', p5, c5);
+    c4.push(vn5);
+    c5.push({text: \`sts rocks\`});
 }"
 `;
 
@@ -107,9 +202,9 @@ exports[`t-slot directive dafault slots can define a default content 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"__template__1\\"
-    var h = this.h;
+    let h = this.h;
     let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
+    let vn4 = h('span', p4, c4);
     const slot5 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
     if (slot5) {
         slot5.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c4, parent: extra.parent || context}));
@@ -120,13 +215,72 @@ exports[`t-slot directive dafault slots can define a default content 1`] = `
 }"
 `;
 
+exports[`t-slot directive default slot next to named slot, with default content 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__2\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    // Component 'Dialog'
+    let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
+    let props2 = {};
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
+        w2.destroy();
+        w2 = false;
+    }
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, utils.combine(context, scope));
+        let pvnode = w2.__owl__.pvnode;
+        c1.push(pvnode);
+    } else {
+        let componentKey2 = \`Dialog\`;
+        let W2 = scope['Dialog'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
+        w2 = new W2(parent, props2);
+        parent.__owl__.cmap['__3__'] = w2.__owl__.id;
+        w2.__owl__.slotId = 1;
+        let fiber = w2.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {w2.destroy();}}});
+        c1.push(pvnode);
+        w2.__owl__.pvnode = pvnode;
+    }
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    return vn1;
+}"
+`;
+
 exports[`t-slot directive default slot work with text nodes 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
-    c1.push({text: \`sts rocks\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
+    c4.push({text: \`sts rocks\`});
+}"
+`;
+
+exports[`t-slot directive dynamic t-slot call 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__1\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c9 = [], p9 = {key:9,on:{}};
+    let vn9 = h('button', p9, c9);
+    extra.handlers['click__10__'] = extra.handlers['click__10__'] || function (e) {if (context.__owl__.status === 5){return}utils.getComponent(context)['toggle'](e);};
+    p9.on['click'] = extra.handlers['click__10__'];
+    const slot11 = this.constructor.slots[context.__owl__.slotId + '_' + (scope['current'].slot)];
+    if (slot11) {
+        slot11.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c9, parent: extra.parent || context}));
+    }
+    return vn9;
 }"
 `;
 
@@ -134,16 +288,17 @@ exports[`t-slot directive multiple roots are allowed in a default slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
-    c1.push(vn4);
-    c4.push({text: \`sts\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
-    var vn5 = h('span', p5, c5);
-    c1.push(vn5);
-    c5.push({text: \`rocks\`});
+    let vn5 = h('span', p5, c5);
+    c4.push(vn5);
+    c5.push({text: \`sts\`});
+    let c6 = [], p6 = {key:6};
+    let vn6 = h('span', p6, c6);
+    c4.push(vn6);
+    c6.push({text: \`rocks\`});
 }"
 `;
 
@@ -151,16 +306,17 @@ exports[`t-slot directive multiple roots are allowed in a named slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_content_template\\"
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
-    c1.push(vn4);
-    c4.push({text: \`sts\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
-    var vn5 = h('span', p5, c5);
-    c1.push(vn5);
-    c5.push({text: \`rocks\`});
+    let vn5 = h('span', p5, c5);
+    c4.push(vn5);
+    c5.push({text: \`sts\`});
+    let c6 = [], p6 = {key:6};
+    let vn6 = h('span', p6, c6);
+    c4.push(vn6);
+    c6.push({text: \`rocks\`});
 }"
 `;
 
@@ -168,9 +324,9 @@ exports[`t-slot directive named slots can define a default content 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"__template__1\\"
-    var h = this.h;
+    let h = this.h;
     let c4 = [], p4 = {key:4};
-    var vn4 = h('span', p4, c4);
+    let vn4 = h('span', p4, c4);
     const slot5 = this.constructor.slots[context.__owl__.slotId + '_' + 'header'];
     if (slot5) {
         slot5.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c4, parent: extra.parent || context}));
@@ -186,24 +342,25 @@ exports[`t-slot directive refs are properly bound in slots 1`] = `
 ) {
     // Template name: \\"slot_footer_template\\"
     let utils = this.constructor.utils;
+    let parent = extra.parent;
     context.__owl__.refs = context.__owl__.refs || {};
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c8 = [], p8 = {key:8,on:{}};
-    var vn8 = h('button', p8, c8);
-    c1.push(vn8);
-    extra.handlers['click__9__'] = extra.handlers['click__9__'] || function (e) {if (!context.__owl__.isMounted){return}utils.getComponent(context)['doSomething'](e);};
-    p8.on['click'] = extra.handlers['click__9__'];
-    const ref10 = \`myButton\`;
-    p8.hook = {
+    let h = this.h;
+    let c8 = extra.parentNode;
+    let c9 = [], p9 = {key:9,on:{}};
+    let vn9 = h('button', p9, c9);
+    c8.push(vn9);
+    extra.handlers['click__10__'] = extra.handlers['click__10__'] || function (e) {if (context.__owl__.status === 5){return}utils.getComponent(context)['doSomething'](e);};
+    p9.on['click'] = extra.handlers['click__10__'];
+    const ref11 = \`myButton\`;
+    p9.hook = {
       create: (_, n) => {
-        context.__owl__.refs[ref10] = n.elm;
+        context.__owl__.refs[ref11] = n.elm;
       },
       destroy: () => {
-        delete context.__owl__.refs[ref10];
+        delete context.__owl__.refs[ref11];
       },
     };
-    c8.push({text: \`do something\`});
+    c9.push({text: \`do something\`});
 }"
 `;
 
@@ -212,14 +369,15 @@ exports[`t-slot directive slots are rendered with proper context 1`] = `
 ) {
     // Template name: \\"slot_footer_template\\"
     let utils = this.constructor.utils;
-    var h = this.h;
-    let c1 = extra.parentNode;
-    let c8 = [], p8 = {key:8,on:{}};
-    var vn8 = h('button', p8, c8);
-    c1.push(vn8);
-    extra.handlers['click__9__'] = extra.handlers['click__9__'] || function (e) {if (!context.__owl__.isMounted){return}utils.getComponent(context)['doSomething'](e);};
-    p8.on['click'] = extra.handlers['click__9__'];
-    c8.push({text: \`do something\`});
+    let parent = extra.parent;
+    let h = this.h;
+    let c8 = extra.parentNode;
+    let c9 = [], p9 = {key:9,on:{}};
+    let vn9 = h('button', p9, c9);
+    c8.push(vn9);
+    extra.handlers['click__10__'] = extra.handlers['click__10__'] || function (e) {if (context.__owl__.status === 5){return}utils.getComponent(context)['doSomething'](e);};
+    p9.on['click'] = extra.handlers['click__10__'];
+    c9.push({text: \`do something\`});
 }"
 `;
 
@@ -228,10 +386,10 @@ exports[`t-slot directive slots are rendered with proper context, part 2 1`] = `
 ) {
     // Template name: \\"Link\\"
     let scope = Object.create(context);
-    var h = this.h;
-    var _12 = scope['props'].to;
+    let h = this.h;
+    let _12 = scope['props'].to;
     let c13 = [], p13 = {key:13,attrs:{href: _12}};
-    var vn13 = h('a', p13, c13);
+    let vn13 = h('a', p13, c13);
     const slot14 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
     if (slot14) {
         slot14.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c13, parent: extra.parent || context}));
@@ -248,57 +406,58 @@ exports[`t-slot directive slots are rendered with proper context, part 2 2`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     let c2 = [], p2 = {key:2};
-    var vn2 = h('u', p2, c2);
+    let vn2 = h('u', p2, c2);
     c1.push(vn2);
-    var _3 = scope['state'].users;
+    let _3 = scope['state'].users;
     if (!_3) { throw new Error('QWeb error: Invalid loop expression')}
-    var _4 = _5 = _3;
+    let _4 = _3;
+    let _5 = _3;
     if (!(_3 instanceof Array)) {
         _4 = Object.keys(_3);
         _5 = Object.values(_3);
     }
-    var _length4 = _4.length;
-    const _origScope6 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    let _length4 = _4.length;
+    let _origScope6 = scope;
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length4; i1++) {
         scope.user_first = i1 === 0
         scope.user_last = i1 === _length4 - 1
         scope.user_index = i1
         scope.user = _4[i1]
         scope.user_value = _5[i1]
-        const nodeKey7 = scope['user'].id;
-        let c8 = [], p8 = {key:nodeKey7};
-        var vn8 = h('li', p8, c8);
-        c2.push(vn8);
+        let key1 = scope['user'].id;
+        let c7 = [], p7 = {key:\`\${key1}_7\`};
+        let vn7 = h('li', p7, c7);
+        c2.push(vn7);
         // Component 'Link'
-        let k10 = \`__10__\` + nodeKey7;
-        let w9 = k10 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k10]] : false;
-        let props9 = {to:'/user/'+scope['user'].id};
-        if (w9 && w9.__owl__.currentFiber && !w9.__owl__.vnode) {
-            w9.destroy();
-            w9 = false;
+        let k9 = \`__9__\${key1}__\`;
+        let w8 = k9 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k9]] : false;
+        let props8 = {to:'/user/'+scope['user'].id};
+        if (w8 && w8.__owl__.currentFiber && !w8.__owl__.vnode) {
+            w8.destroy();
+            w8 = false;
         }
-        if (w9) {
-            w9.__updateProps(props9, extra.fiber, Object.assign(Object.create(context), scope));
-            let pvnode = w9.__owl__.pvnode;
-            c8.push(pvnode);
+        if (w8) {
+            w8.__updateProps(props8, extra.fiber, utils.combine(context, scope));
+            let pvnode = w8.__owl__.pvnode;
+            c7.push(pvnode);
         } else {
-            let componentKey9 = \`Link\`;
-            let W9 = context.constructor.components[componentKey9] || QWeb.components[componentKey9]|| scope['Link'];
-            if (!W9) {throw new Error('Cannot find the definition of component \\"' + componentKey9 + '\\"')}
-            w9 = new W9(parent, props9);
-            parent.__owl__.cmap[k10] = w9.__owl__.id;
-            w9.__owl__.slotId = 1;
-            let fiber = w9.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k10, hook: {remove() {},destroy(vn) {w9.destroy();}}});
-            c8.push(pvnode);
-            w9.__owl__.pvnode = pvnode;
+            let componentKey8 = \`Link\`;
+            let W8 = scope['Link'] || context.constructor.components[componentKey8] || QWeb.components[componentKey8];
+            if (!W8) {throw new Error('Cannot find the definition of component \\"' + componentKey8 + '\\"')}
+            w8 = new W8(parent, props8);
+            parent.__owl__.cmap[k9] = w8.__owl__.id;
+            w8.__owl__.slotId = 1;
+            let fiber = w8.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            let pvnode = h('dummy', {key: k9, hook: {remove() {},destroy(vn) {w8.destroy();}}});
+            c7.push(pvnode);
+            w8.__owl__.pvnode = pvnode;
         }
-        w9.__owl__.parentLastFiberId = extra.fiber.id;
+        w8.__owl__.parentLastFiberId = extra.fiber.id;
     }
     scope = _origScope6;
     return vn1;
@@ -309,13 +468,14 @@ exports[`t-slot directive slots are rendered with proper context, part 2 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
-    var h = this.h;
-    let c8 = extra.parentNode;
-    c8.push({text: \`User \`});
-    var _11 = scope['user'].name;
-    if (_11 || _11 === 0) {
-        c8.push({text: _11});
+    let h = this.h;
+    let c10 = extra.parentNode;
+    c10.push({text: \`User \`});
+    let _11 = scope['user'].name;
+    if (_11 != null) {
+        c10.push({text: _11});
     }
 }"
 `;
@@ -325,15 +485,15 @@ exports[`t-slot directive slots are rendered with proper context, part 3 1`] = `
 ) {
     // Template name: \\"Link\\"
     let scope = Object.create(context);
-    var h = this.h;
-    var _11 = scope['props'].to;
-    let c12 = [], p12 = {key:12,attrs:{href: _11}};
-    var vn12 = h('a', p12, c12);
-    const slot13 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot13) {
-        slot13.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c12, parent: extra.parent || context}));
+    let h = this.h;
+    let _12 = scope['props'].to;
+    let c13 = [], p13 = {key:13,attrs:{href: _12}};
+    let vn13 = h('a', p13, c13);
+    const slot14 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot14) {
+        slot14.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c13, parent: extra.parent || context}));
     }
-    return vn12;
+    return vn13;
 }"
 `;
 
@@ -345,58 +505,59 @@ exports[`t-slot directive slots are rendered with proper context, part 3 2`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     let c2 = [], p2 = {key:2};
-    var vn2 = h('u', p2, c2);
+    let vn2 = h('u', p2, c2);
     c1.push(vn2);
-    var _3 = scope['state'].users;
+    let _3 = scope['state'].users;
     if (!_3) { throw new Error('QWeb error: Invalid loop expression')}
-    var _4 = _5 = _3;
+    let _4 = _3;
+    let _5 = _3;
     if (!(_3 instanceof Array)) {
         _4 = Object.keys(_3);
         _5 = Object.values(_3);
     }
-    var _length4 = _4.length;
-    const _origScope6 = scope;
-    scope = Object.assign(Object.create(context), scope);
+    let _length4 = _4.length;
+    let _origScope6 = scope;
+    scope = Object.create(scope);
     for (let i1 = 0; i1 < _length4; i1++) {
         scope.user_first = i1 === 0
         scope.user_last = i1 === _length4 - 1
         scope.user_index = i1
         scope.user = _4[i1]
         scope.user_value = _5[i1]
-        const nodeKey7 = scope['user'].id;
-        let c8 = [], p8 = {key:nodeKey7};
-        var vn8 = h('li', p8, c8);
-        c2.push(vn8);
-        scope.userdescr = 'User '+scope['user'].name;
+        let key1 = scope['user'].id;
+        let c7 = [], p7 = {key:\`\${key1}_7\`};
+        let vn7 = h('li', p7, c7);
+        c2.push(vn7);
+        utils.getScope(scope, 'userdescr').userdescr = 'User '+scope['user'].name;
         // Component 'Link'
-        let k10 = \`__10__\` + nodeKey7;
-        let w9 = k10 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k10]] : false;
-        let props9 = {to:'/user/'+scope['user'].id};
-        if (w9 && w9.__owl__.currentFiber && !w9.__owl__.vnode) {
-            w9.destroy();
-            w9 = false;
+        let k9 = \`__9__\${key1}__\`;
+        let w8 = k9 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k9]] : false;
+        let props8 = {to:'/user/'+scope['user'].id};
+        if (w8 && w8.__owl__.currentFiber && !w8.__owl__.vnode) {
+            w8.destroy();
+            w8 = false;
         }
-        if (w9) {
-            w9.__updateProps(props9, extra.fiber, Object.assign(Object.create(context), scope));
-            let pvnode = w9.__owl__.pvnode;
-            c8.push(pvnode);
+        if (w8) {
+            w8.__updateProps(props8, extra.fiber, utils.combine(context, scope));
+            let pvnode = w8.__owl__.pvnode;
+            c7.push(pvnode);
         } else {
-            let componentKey9 = \`Link\`;
-            let W9 = context.constructor.components[componentKey9] || QWeb.components[componentKey9]|| scope['Link'];
-            if (!W9) {throw new Error('Cannot find the definition of component \\"' + componentKey9 + '\\"')}
-            w9 = new W9(parent, props9);
-            parent.__owl__.cmap[k10] = w9.__owl__.id;
-            w9.__owl__.slotId = 1;
-            let fiber = w9.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k10, hook: {remove() {},destroy(vn) {w9.destroy();}}});
-            c8.push(pvnode);
-            w9.__owl__.pvnode = pvnode;
+            let componentKey8 = \`Link\`;
+            let W8 = scope['Link'] || context.constructor.components[componentKey8] || QWeb.components[componentKey8];
+            if (!W8) {throw new Error('Cannot find the definition of component \\"' + componentKey8 + '\\"')}
+            w8 = new W8(parent, props8);
+            parent.__owl__.cmap[k9] = w8.__owl__.id;
+            w8.__owl__.slotId = 1;
+            let fiber = w8.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            let pvnode = h('dummy', {key: k9, hook: {remove() {},destroy(vn) {w8.destroy();}}});
+            c7.push(pvnode);
+            w8.__owl__.pvnode = pvnode;
         }
-        w9.__owl__.parentLastFiberId = extra.fiber.id;
+        w8.__owl__.parentLastFiberId = extra.fiber.id;
     }
     scope = _origScope6;
     return vn1;
@@ -407,11 +568,13 @@ exports[`t-slot directive slots are rendered with proper context, part 3 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
-    var h = this.h;
-    let c8 = extra.parentNode;
-    if (scope.userdescr || scope.userdescr === 0) {
-        c8.push({text: scope.userdescr});
+    let h = this.h;
+    let c10 = extra.parentNode;
+    let _11 = scope['userdescr'];
+    if (_11 != null) {
+        c10.push({text: _11});
     }
 }"
 `;
@@ -424,9 +587,9 @@ exports[`t-slot directive slots are rendered with proper context, part 4 1`] = `
     let QWeb = this.constructor;
     let parent = context;
     let scope = Object.create(context);
-    var h = this.h;
+    let h = this.h;
     let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
+    let vn1 = h('div', p1, c1);
     scope.userdescr = 'User '+scope['state'].user.name;
     // Component 'Link'
     let w2 = '__3__' in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap['__3__']] : false;
@@ -436,17 +599,17 @@ exports[`t-slot directive slots are rendered with proper context, part 4 1`] = `
         w2 = false;
     }
     if (w2) {
-        w2.__updateProps(props2, extra.fiber, Object.assign(Object.create(context), scope));
+        w2.__updateProps(props2, extra.fiber, utils.combine(context, scope));
         let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
         let componentKey2 = \`Link\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Link'];
+        let W2 = scope['Link'] || context.constructor.components[componentKey2] || QWeb.components[componentKey2];
         if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
         w2 = new W2(parent, props2);
         parent.__owl__.cmap['__3__'] = w2.__owl__.id;
         w2.__owl__.slotId = 1;
-        let fiber = w2.__prepare(extra.fiber, Object.assign(Object.create(context), scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        let fiber = w2.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         let pvnode = h('dummy', {key: '__3__', hook: {remove() {},destroy(vn) {w2.destroy();}}});
         c1.push(pvnode);
         w2.__owl__.pvnode = pvnode;
@@ -460,28 +623,135 @@ exports[`t-slot directive slots are rendered with proper context, part 4 2`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
-    var h = this.h;
-    let c1 = extra.parentNode;
-    if (scope.userdescr || scope.userdescr === 0) {
-        c1.push({text: scope.userdescr});
+    let h = this.h;
+    let c4 = extra.parentNode;
+    let _5 = scope['userdescr'];
+    if (_5 != null) {
+        c4.push({text: _5});
     }
 }"
 `;
 
+exports[`t-slot directive slots in t-foreach in t-foreach 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__2\\"
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    let _2 = scope['tree'];
+    if (!_2) { throw new Error('QWeb error: Invalid loop expression')}
+    let _3 = _2;
+    let _4 = _2;
+    if (!(_2 instanceof Array)) {
+        _3 = Object.keys(_2);
+        _4 = Object.values(_2);
+    }
+    let _length3 = _3.length;
+    let _origScope5 = scope;
+    scope = Object.create(scope);
+    for (let i1 = 0; i1 < _length3; i1++) {
+        scope.node1_first = i1 === 0
+        scope.node1_last = i1 === _length3 - 1
+        scope.node1_index = i1
+        scope.node1 = _3[i1]
+        scope.node1_value = _4[i1]
+        let key1 = scope['node1'].key;
+        let c6 = [], p6 = {key:\`\${key1}_6\`};
+        let vn6 = h('div', p6, c6);
+        c1.push(vn6);
+        let _7 = scope['node1'].value;
+        if (_7 != null) {
+            c6.push({text: _7});
+        }
+        let c8 = [], p8 = {key:\`\${key1}_8\`};
+        let vn8 = h('ul', p8, c8);
+        c1.push(vn8);
+        let _9 = scope['node1'].nodes;
+        if (!_9) { throw new Error('QWeb error: Invalid loop expression')}
+        let _10 = _9;
+        let _11 = _9;
+        if (!(_9 instanceof Array)) {
+            _10 = Object.keys(_9);
+            _11 = Object.values(_9);
+        }
+        let _length10 = _10.length;
+        let _origScope12 = scope;
+        scope = Object.create(scope);
+        for (let i2 = 0; i2 < _length10; i2++) {
+            scope.node2_first = i2 === 0
+            scope.node2_last = i2 === _length10 - 1
+            scope.node2_index = i2
+            scope.node2 = _10[i2]
+            scope.node2_value = _11[i2]
+            let key2 = scope['node2'].key;
+            // Component 'Child'
+            let k14 = \`__14__\${key1}__\${key2}__\`;
+            let w13 = k14 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k14]] : false;
+            let props13 = {};
+            if (w13 && w13.__owl__.currentFiber && !w13.__owl__.vnode) {
+                w13.destroy();
+                w13 = false;
+            }
+            if (w13) {
+                w13.__updateProps(props13, extra.fiber, utils.combine(context, scope));
+                let pvnode = w13.__owl__.pvnode;
+                c8.push(pvnode);
+            } else {
+                let componentKey13 = \`Child\`;
+                let W13 = scope['Child'] || context.constructor.components[componentKey13] || QWeb.components[componentKey13];
+                if (!W13) {throw new Error('Cannot find the definition of component \\"' + componentKey13 + '\\"')}
+                w13 = new W13(parent, props13);
+                parent.__owl__.cmap[k14] = w13.__owl__.id;
+                w13.__owl__.slotId = 1;
+                let fiber = w13.__prepare(extra.fiber, utils.combine(context, scope), () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+                let pvnode = h('dummy', {key: k14, hook: {remove() {},destroy(vn) {w13.destroy();}}});
+                c8.push(pvnode);
+                w13.__owl__.pvnode = pvnode;
+            }
+            w13.__owl__.parentLastFiberId = extra.fiber.id;
+        }
+        scope = _origScope12;
+    }
+    scope = _origScope5;
+    return vn1;
+}"
+`;
+
+exports[`t-slot directive t-set t-value in a slot 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"__template__1\\"
+    let h = this.h;
+    let c5 = [], p5 = {key:5};
+    let vn5 = h('span', p5, c5);
+    const slot6 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot6) {
+        slot6.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c5, parent: extra.parent || context}));
+    }
+    return vn5;
+}"
+`;
+
 exports[`t-slot directive template can just return a slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"__template__2\\"
     let utils = this.constructor.utils;
     let result;
-    var h = this.h;
-    const slot6 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot6) {
-        let children7= []
+    let h = this.h;
+    const slot7 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot7) {
+        let children8= []
         result = {}
-        slot6.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: children7, parent: extra.parent || context}));
-        utils.defineProxy(result, children7[0]);
+        slot7.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: children8, parent: extra.parent || context}));
+        utils.defineProxy(result, children8[0]);
     }
     return result;
 }"

tests/component/class_style.test.ts

@@ -0,0 +1,273 @@
+import { Component, Env } from "../../src/component/component";
+import { QWeb } from "../../src/qweb/qweb";
+import { xml } from "../../src/tags";
+import { useState, useRef } from "../../src/hooks";
+import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: a WEnv, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+  Component.env = env;
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("class and style attributes with t-component", () => {
+  test("class is properly added on widget root el", async () => {
+    class Child extends Component {
+      static template = xml`<div class="c"/>`;
+    }
+    class ParentWidget extends Component {
+      static template = xml`<div><Child class="a b"/></div>`;
+      static components = { Child };
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(`<div><div class="c a b"></div></div>`);
+  });
+
+  test("empty class attribute is not added on widget root el", async () => {
+    class Child extends Component {
+      static template = xml`<span/>`;
+    }
+    class Parent extends Component {
+      static template = xml`<div><Child class=""/></div>`;
+      static components = { Child };
+    }
+    const widget = new Parent();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(`<div><span></span></div>`);
+  });
+
+  test("t-att-class is properly added/removed on widget root el", async () => {
+    class Child extends Component {
+      static template = xml`<div class="c"/>`;
+    }
+    class ParentWidget extends Component {
+      static template = xml`<div><Child t-att-class="{a:state.a, b:state.b}"/></div>`;
+      static components = { Child };
+      state = useState({ a: true, b: false });
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(`<div><div class="c a"></div></div>`);
+    expect(QWeb.TEMPLATES[ParentWidget.template].fn.toString());
+
+    widget.state.a = false;
+    widget.state.b = true;
+    await nextTick();
+    expect(fixture.innerHTML).toBe(`<div><div class="c b"></div></div>`);
+  });
+
+  test("class with extra whitespaces", async () => {
+    env.qweb.addTemplate(
+      "ParentWidget",
+      `<div>
+              <Child class="a  b c   d"/>
+        </div>`
+    );
+    class Child extends Component {}
+    class ParentWidget extends Component {
+      static components = { Child };
+    }
+    env.qweb.addTemplate("Child", `<div/>`);
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(`<div><div class="a b c d"></div></div>`);
+  });
+
+  test("t-att-class is properly added/removed on widget root el (v2)", async () => {
+    env.qweb.addTemplates(`
+        <templates>
+          <div t-name="ParentWidget">
+            <Child class="a" t-att-class="{ b: state.b }" t-ref="child"/>
+          </div>
+          <span t-name="Child" class="c" t-att-class="{ d: state.d }"/>
+        </templates>`);
+
+    class Child extends Component {
+      state = useState({ d: true });
+    }
+    class ParentWidget extends Component {
+      static components = { Child };
+      state = useState({ b: true });
+      child = useRef("child");
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+
+    const span = fixture.querySelector("span")!;
+    expect(span.className).toBe("c d a b");
+
+    widget.state.b = false;
+    await nextTick();
+    expect(span.className).toBe("c d a");
+
+    (widget.child.comp as Child).state.d = false;
+    await nextTick();
+    expect(span.className).toBe("c a");
+
+    widget.state.b = true;
+    await nextTick();
+    expect(span.className).toBe("c a b");
+
+    (widget.child.comp as Child).state.d = true;
+    await nextTick();
+    expect(span.className).toBe("c a b d");
+    expect(env.qweb.templates.ParentWidget.fn.toString()).toMatchSnapshot();
+    expect(env.qweb.templates.Child.fn.toString()).toMatchSnapshot();
+  });
+
+  test("t-att-class is properly added/removed on widget root el (v3)", async () => {
+    env.qweb.addTemplates(`
+        <templates>
+          <div t-name="ParentWidget">
+            <Child class="a" t-att-class="state.b ? 'b' : ''" t-ref="child"/>
+          </div>
+          <span t-name="Child" class="c" t-att-class="state.d ? 'd' : ''"/>
+        </templates>`);
+
+    class Child extends Component {
+      state = useState({ d: true });
+    }
+    class ParentWidget extends Component {
+      static components = { Child };
+      state = useState({ b: true });
+      child = useRef("child");
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+
+    const span = fixture.querySelector("span")!;
+    expect(span.className).toBe("c d a b");
+
+    widget.state.b = false;
+    await nextTick();
+    expect(span.className).toBe("c d a");
+
+    (widget.child.comp as Child).state.d = false;
+    await nextTick();
+    expect(span.className).toBe("c a");
+
+    widget.state.b = true;
+    await nextTick();
+    expect(span.className).toBe("c a b");
+
+    (widget.child.comp as Child).state.d = true;
+    await nextTick();
+    expect(span.className).toBe("c a b d");
+    expect(env.qweb.templates.ParentWidget.fn.toString()).toMatchSnapshot();
+    expect(env.qweb.templates.Child.fn.toString()).toMatchSnapshot();
+  });
+
+  test("class on components do not interfere with user defined classes", async () => {
+    env.qweb.addTemplates(`
+        <templates>
+          <div t-name="App" t-att-class="{ c: state.c }" />
+        </templates>`);
+
+    class App extends Component {
+      state = useState({ c: true });
+      mounted() {
+        this.el!.classList.add("user");
+      }
+    }
+
+    const widget = new App();
+    await widget.mount(fixture);
+
+    expect(fixture.innerHTML).toBe('<div class="c user"></div>');
+
+    widget.state.c = false;
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe('<div class="user"></div>');
+  });
+
+  test("style is properly added on widget root el", async () => {
+    env.qweb.addTemplate(
+      "ParentWidget",
+      `
+          <div>
+              <t t-component="child" style="font-weight: bold;"/>
+          </div>`
+    );
+
+    class SomeComponent extends Component {
+      static template = xml`<div/>`;
+    }
+
+    class ParentWidget extends Component {
+      static components = { child: SomeComponent };
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe(`<div><div style="font-weight: bold;"></div></div>`);
+  });
+
+  test("dynamic t-att-style is properly added and updated on widget root el", async () => {
+    env.qweb.addTemplate(
+      "ParentWidget",
+      `
+          <div>
+              <t t-component="child" t-att-style="state.style"/>
+          </div>`
+    );
+
+    class SomeComponent extends Component {
+      static template = xml`<div/>`;
+    }
+
+    class ParentWidget extends Component {
+      static components = { child: SomeComponent };
+      state = useState({ style: "font-size: 20px" });
+    }
+    const widget = new ParentWidget();
+    await widget.mount(fixture);
+
+    expect(env.qweb.templates.ParentWidget.fn.toString()).toMatchSnapshot();
+
+    expect(fixture.innerHTML).toBe(`<div><div style="font-size: 20px;"></div></div>`);
+
+    widget.state.style = "font-size: 30px";
+    await nextTick();
+
+    expect(fixture.innerHTML).toBe(`<div><div style="font-size: 30px;"></div></div>`);
+  });
+
+  test("error in subcomponent with class", async () => {
+    class Child extends Component {
+      static template = xml`<div t-esc="this.will.crash"/>`;
+    }
+    class ParentWidget extends Component {
+      static template = xml`<div><Child class="a"/></div>`;
+      static components = { Child };
+    }
+    const widget = new ParentWidget();
+    let error;
+    try {
+      await widget.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    const regexp =
+      /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
+    expect(error.message).toMatch(regexp);
+    expect(fixture.innerHTML).toBe("");
+  });
+});

tests/component/error_handling.test.ts

@@ -0,0 +1,620 @@
+import { Component, Env, mount, STATUS } from "../../src/component/component";
+import { useState } from "../../src/hooks";
+import { xml } from "../../src/tags";
+import { makeTestEnv, makeTestFixture, nextTick } from "../helpers";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: a WEnv, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+  Component.env = env;
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("component error handling (catchError)", () => {
+  /**
+   * This test suite requires often to wait for 3 ticks. Here is why:
+   * - First tick is to let the app render and crash.
+   * - When we crash, we call the catchError handler in a setTimeout (because we
+   *   need to wait for the previous rendering to be completely stopped). So, we
+   *   need to wait for the second tick.
+   * - Then, when the handler changes the state, we need to wait for the interface
+   *   to be rerendered.
+   *  */
+
+  test("can catch an error in a component render function", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn();
+    const handler = jest.fn();
+    env.qweb.on("error", null, handler);
+    class ErrorComponent extends Component {
+      static template = xml`<div>hey<t t-esc="props.flag and state.this.will.crash"/></div>`;
+    }
+    class ErrorBoundary extends Component {
+      static template = xml`
+          <div>
+            <t t-if="state.error">Error handled</t>
+            <t t-else=""><t t-slot="default" /></t>
+          </div>`;
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static template = xml`
+          <div>
+            <ErrorBoundary><ErrorComponent flag="state.flag"/></ErrorBoundary>
+          </div>`;
+      state = useState({ flag: false });
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div><div>heyfalse</div></div></div>");
+    app.state.flag = true;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+    expect(handler).toBeCalledTimes(1);
+  });
+
+  test("no component catching error lead to full app destruction", async () => {
+    expect.assertions(6);
+    const handler = jest.fn();
+    env.qweb.on("error", null, handler);
+    const consoleError = console.error;
+    console.error = jest.fn();
+
+    class ErrorComponent extends Component {
+      static template = xml`<div>hey<t t-esc="props.flag and state.this.will.crash"/></div>`;
+    }
+
+    class App extends Component {
+      static template = xml`<div><ErrorComponent flag="state.flag"/></div>`;
+      static components = { ErrorComponent };
+      state = useState({ flag: false });
+      async render() {
+        try {
+          await super.render();
+        } catch (e) {
+          expect(e.message).toMatch(
+            /Cannot read properties of undefined \(reading 'this'\)|Cannot read property 'this' of undefined/
+          );
+        }
+      }
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>heyfalse</div></div>");
+    app.state.flag = true;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+    expect(app.__owl__.status).toBe(STATUS.DESTROYED);
+    expect(handler).toBeCalledTimes(1);
+  });
+
+  test("can catch an error in the initial call of a component render function (parent mounted)", async () => {
+    const handler = jest.fn();
+    env.qweb.on("error", null, handler);
+    const consoleError = console.error;
+    console.error = jest.fn();
+    class ErrorComponent extends Component {
+      static template = xml`<div>hey<t t-esc="state.this.will.crash"/></div>`;
+    }
+    class ErrorBoundary extends Component {
+      static template = xml`
+          <div>
+            <t t-if="state.error">Error handled</t>
+            <t t-else=""><t t-slot="default" /></t>
+          </div>`;
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static template = xml`
+          <div>
+              <ErrorBoundary><ErrorComponent /></ErrorBoundary>
+          </div>`;
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+    expect(handler).toBeCalledTimes(1);
+  });
+
+  test("can catch an error in the initial call of a component render function (parent updated)", async () => {
+    const handler = jest.fn();
+    env.qweb.on("error", null, handler);
+    const consoleError = console.error;
+    console.error = jest.fn();
+    class ErrorComponent extends Component {
+      static template = xml`<div>hey<t t-esc="state.this.will.crash"/></div>`;
+    }
+    class ErrorBoundary extends Component {
+      static template = xml`
+          <div>
+            <t t-if="state.error">Error handled</t>
+            <t t-else=""><t t-slot="default" /></t>
+          </div>`;
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static template = xml`
+          <div>
+              <ErrorBoundary t-if="state.flag"><ErrorComponent /></ErrorBoundary>
+          </div>`;
+      state = useState({ flag: false });
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    app.state.flag = true;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+    expect(handler).toBeCalledTimes(1);
+  });
+
+  test("can catch an error in the constructor call of a component render function", async () => {
+    const handler = jest.fn();
+    env.qweb.on("error", null, handler);
+    const consoleError = console.error;
+    console.error = jest.fn();
+    env.qweb.addTemplates(`
+        <templates>
+          <div t-name="ErrorBoundary">
+              <t t-if="state.error">Error handled</t>
+              <t t-else=""><t t-slot="default" /></t>
+          </div>
+          <div t-name="ErrorComponent">Some text</div>
+          <div t-name="App">
+              <ErrorBoundary><ErrorComponent /></ErrorBoundary>
+          </div>
+        </templates>`);
+    class ErrorComponent extends Component {
+      constructor(parent) {
+        super(parent);
+        throw new Error("NOOOOO");
+      }
+    }
+    class ErrorBoundary extends Component {
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+    expect(handler).toBeCalledTimes(1);
+  });
+
+  test("can catch an error in the willStart call", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn();
+    class ErrorComponent extends Component {
+      static template = xml`<div t-name="ErrorComponent">Some text</div>`;
+      async willStart() {
+        // we wait a little bit to be in a different stack frame
+        await nextTick();
+        throw new Error("NOOOOO");
+      }
+    }
+    class ErrorBoundary extends Component {
+      static template = xml`
+          <div>
+            <t t-if="state.error">Error handled</t>
+            <t t-else=""><t t-slot="default" /></t>
+          </div>`;
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static template = xml`<div><ErrorBoundary><ErrorComponent /></ErrorBoundary></div>`;
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test.skip("can catch an error in the mounted call", async () => {
+    // we do not catch error in mounted anymore
+    console.error = jest.fn();
+    env.qweb.addTemplates(`
+        <templates>
+          <div t-name="ErrorBoundary">
+              <t t-if="state.error">Error handled</t>
+              <t t-else=""><t t-slot="default" /></t>
+          </div>
+          <div t-name="ErrorComponent">Some text</div>
+          <div t-name="App">
+              <ErrorBoundary><ErrorComponent /></ErrorBoundary>
+          </div>
+        </templates>`);
+    class ErrorComponent extends Component {
+      mounted() {
+        throw new Error("NOOOOO");
+      }
+    }
+    class ErrorBoundary extends Component {
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    await nextTick();
+    await nextTick();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>Error handled</div></div>");
+  });
+
+  test.skip("can catch an error in the willPatch call", async () => {
+    // we do not catch error in willPatch anymore
+    const consoleError = console.error;
+    console.error = jest.fn();
+    class ErrorComponent extends Component {
+      static template = xml`<div><t t-esc="props.message"/></div>`;
+      willPatch() {
+        throw new Error("NOOOOO");
+      }
+    }
+    class ErrorBoundary extends Component {
+      static template = xml`
+          <div>
+            <t t-if="state.error">Error handled</t>
+            <t t-else=""><t t-slot="default" /></t>
+          </div>`;
+      state = useState({ error: false });
+
+      catchError() {
+        this.state.error = true;
+      }
+    }
+    class App extends Component {
+      static template = xml`
+          <div>
+              <span><t t-esc="state.message"/></span>
+            <ErrorBoundary><ErrorComponent message="state.message" /></ErrorBoundary>
+          </div>`;
+      state = useState({ message: "abc" });
+      static components = { ErrorBoundary, ErrorComponent };
+    }
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><span>abc</span><div><div>abc</div></div></div>");
+    app.state.message = "def";
+    await nextTick();
+    await nextTick();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>def</span><div>Error handled</div></div>");
+    expect(console.error).toHaveBeenCalledTimes(1);
+    console.error = consoleError;
+  });
+
+  test("a rendering error will reject the mount promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+    // we do not catch error in willPatch anymore
+    class App extends Component {
+      static template = xml`<div><t t-esc="this.will.crash"/></div>`;
+    }
+
+    const app = new App();
+    let error;
+    try {
+      await app.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    const regexp =
+      /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
+    expect(error.message).toMatch(regexp);
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("an error in mounted call will reject the mount promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class App extends Component {
+      static template = xml`<div>abc</div>`;
+      mounted() {
+        throw new Error("boom");
+      }
+    }
+
+    const app = new App();
+    let error;
+    try {
+      await app.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("boom");
+    expect(fixture.innerHTML).toBe("");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("an error in willPatch call will reject the render promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class App extends Component {
+      static template = xml`<div><t t-esc="val"/></div>`;
+      val = 3;
+      willPatch() {
+        throw new Error("boom");
+      }
+    }
+
+    const app = new App();
+    await app.mount(fixture);
+    app.val = 4;
+    let error;
+    try {
+      await app.render();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("boom");
+    expect(fixture.innerHTML).toBe("");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("an error in patched call will reject the render promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class App extends Component {
+      static template = xml`<div><t t-esc="val"/></div>`;
+      val = 3;
+      patched() {
+        throw new Error("boom");
+      }
+    }
+
+    const app = new App();
+    await app.mount(fixture);
+    app.val = 4;
+    let error;
+    try {
+      await app.render();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("boom");
+    expect(fixture.innerHTML).toBe("");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("a rendering error in a sub component will reject the mount promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+    // we do not catch error in willPatch anymore
+    class Child extends Component {
+      static template = xml`<div><t t-esc="this.will.crash"/></div>`;
+    }
+    class App extends Component {
+      static template = xml`<div><Child/></div>`;
+      static components = { Child };
+    }
+
+    const app = new App();
+    let error;
+    try {
+      await app.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    const regexp =
+      /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
+    expect(error.message).toMatch(regexp);
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("a rendering error will reject the render promise", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+    // we do not catch error in willPatch anymore
+    class App extends Component {
+      static template = xml`<div><t t-if="flag" t-esc="this.will.crash"/></div>`;
+      flag = false;
+    }
+
+    const app = new App();
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div></div>");
+    app.flag = true;
+    let error;
+    try {
+      await app.render();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    const regexp =
+      /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
+    expect(error.message).toMatch(regexp);
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("a rendering error will reject the render promise (with sub components)", async () => {
+    class Child extends Component {
+      static template = xml`<span></span>`;
+    }
+    class Parent extends Component {
+      static template = xml`<div><Child/><t t-esc="x.y"/></div>`;
+      static components = { Child };
+    }
+
+    let error;
+    try {
+      const parent = new Parent();
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    const regexp =
+      /Cannot read properties of undefined \(reading 'y'\)|Cannot read property 'y' of undefined/g;
+    expect(error.message).toMatch(regexp);
+  });
+
+  test("simple catchError", async () => {
+    class Boom extends Component {
+      static template = xml`<div t-esc="a.b.c"/>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <t t-if="error">Error</t>
+          <t t-else="">
+            <Boom />
+          </t>
+        </div>`;
+      static components = { Boom };
+
+      error = false;
+
+      catchError(error) {
+        this.error = error;
+        this.render();
+      }
+    }
+
+    await mount(Parent, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div>Error</div>");
+  });
+
+  test("catchError in catchError", async () => {
+    class Boom extends Component {
+      static template = xml`<div t-esc="a.b.c"/>`;
+    }
+
+    class Child extends Component {
+      static template = xml`
+        <div>
+          <Boom />
+        </div>`;
+      static components = { Boom };
+
+      catchError(error) {
+        throw error;
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`
+        <div>
+          <t t-if="error">Error</t>
+          <t t-else="">
+            <Child />
+          </t>
+        </div>`;
+      static components = { Child };
+
+      error = false;
+
+      catchError(error) {
+        this.error = error;
+        this.render();
+      }
+    }
+
+    await mount(Parent, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div>Error</div>");
+  });
+
+  test("errors in mounted and in willUnmount", async () => {
+    expect.assertions(1);
+    class Example extends Component {
+      static template = xml`<div/>`;
+      val;
+      mounted() {
+        throw new Error("Error in mounted");
+        this.val = { foo: "bar" };
+      }
+      willUnmount() {
+        console.log(this.val.foo);
+      }
+    }
+
+    try {
+      await mount(Example, { target: fixture });
+    } catch (e) {
+      expect(e.message).toBe("Error in mounted");
+    }
+  });
+});

tests/component/props_validation.test.ts

@@ -25,7 +25,7 @@ afterEach(() => {
   QWeb.dev = dev;
 });
 
-class Widget extends Component<any, any> {}
+class Widget extends Component {}
 
 //------------------------------------------------------------------------------
 // Tests
@@ -92,11 +92,11 @@ describe("props validation", () => {
       { type: String, ok: "1", ko: 1 },
       { type: Object, ok: {}, ko: "1" },
       { type: Date, ok: new Date(), ko: "1" },
-      { type: Function, ok: () => {}, ko: "1" }
+      { type: Function, ok: () => {}, ko: "1" },
     ];
 
     let props;
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       get p() {
         return props.p;
@@ -149,18 +149,18 @@ describe("props validation", () => {
       { type: String, ok: "1", ko: 1 },
       { type: Object, ok: {}, ko: "1" },
       { type: Date, ok: new Date(), ko: "1" },
-      { type: Function, ok: () => {}, ko: "1" }
+      { type: Function, ok: () => {}, ko: "1" },
     ];
 
     let props;
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       get p() {
         return props.p;
       }
     }
     for (let test of Tests) {
-      let TestWidget = class extends Component<any, any> {
+      let TestWidget = class extends Component {
         static props = { p: { type: test.type } };
         static template = xml`<div>hey</div>`;
       };
@@ -200,11 +200,11 @@ describe("props validation", () => {
   });
 
   test("can validate a prop with multiple types", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = { p: [String, Boolean] };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -244,11 +244,11 @@ describe("props validation", () => {
   });
 
   test("can validate an optional props", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = { p: { type: String, optional: true } };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -288,11 +288,11 @@ describe("props validation", () => {
   });
 
   test("can validate an array with given primitive type", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = { p: { type: Array, element: String } };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -340,11 +340,11 @@ describe("props validation", () => {
   });
 
   test("can validate an array with multiple sub element types", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = { p: { type: Array, element: [String, Boolean] } };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -393,13 +393,13 @@ describe("props validation", () => {
   });
 
   test("can validate an object with simple shape", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = {
-        p: { type: Object, shape: { id: Number, url: String } }
+        p: { type: Object, shape: { id: Number, url: String } },
       };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -451,19 +451,19 @@ describe("props validation", () => {
   });
 
   test("can validate recursively complicated prop def", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static template = xml`<div>hey</div>`;
       static props = {
         p: {
           type: Object,
           shape: {
             id: Number,
-            url: [Boolean, { type: Array, element: Number }]
-          }
-        }
+            url: [Boolean, { type: Array, element: Number }],
+          },
+        },
       };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="p"/></div>`;
       static components = { TestWidget };
       get p() {
@@ -503,17 +503,17 @@ describe("props validation", () => {
   });
 
   test("can validate optional attributes in nested sub props", () => {
-    class TestComponent extends Component<any, any> {
+    class TestComponent extends Component {
       static props = {
         myprop: {
           type: Array,
           element: {
             type: Object,
             shape: {
-              num: { type: Number, optional: true }
-            }
-          }
-        }
+              num: { type: Number, optional: true },
+            },
+          },
+        },
       };
     }
     let error;
@@ -536,11 +536,11 @@ describe("props validation", () => {
   });
 
   test("can validate with a custom validator", () => {
-    class TestComponent extends Component<any, any> {
+    class TestComponent extends Component {
       static props = {
         size: {
-          validate: e => ["small", "medium", "large"].includes(e)
-        }
+          validate: (e) => ["small", "medium", "large"].includes(e),
+        },
       };
     }
     let error;
@@ -561,13 +561,13 @@ describe("props validation", () => {
   });
 
   test("can validate with a custom validator, and a type", () => {
-    const validator = jest.fn(n => 0 <= n && n <= 10);
-    class TestComponent extends Component<any, any> {
+    const validator = jest.fn((n) => 0 <= n && n <= 10);
+    class TestComponent extends Component {
       static props = {
         n: {
           type: Number,
-          validate: validator
-        }
+          validate: validator,
+        },
       };
     }
     let error;
@@ -738,7 +738,7 @@ describe("props validation", () => {
 
   test("props are validated whenever component is updated", async () => {
     let error;
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static props = { p: { type: Number } };
       static template = xml`<div><t t-esc="props.p"/></div>`;
 
@@ -750,7 +750,7 @@ describe("props validation", () => {
         }
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="state.p"/></div>`;
       static components = { TestWidget };
       state: any = useState({ p: 1 });
@@ -767,12 +767,12 @@ describe("props validation", () => {
   });
 
   test("default values are applied before validating props at update", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static props = { p: { type: Number } };
       static template = xml`<div><t t-esc="props.p"/></div>`;
       static defaultProps = { p: 4 };
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget p="state.p"/></div>`;
       static components = { TestWidget };
       state: any = useState({ p: 1 });
@@ -786,15 +786,40 @@ describe("props validation", () => {
     await nextTick();
     expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
   });
+
+  test("mix of optional and mandatory", async () => {
+    class Child extends Component {
+      static props = {
+        optional: { type: String, optional: true },
+        mandatory: Number,
+      };
+      static template = xml` <div><t t-esc="props.mandatory"/></div>`;
+    }
+
+    class App extends Component {
+      static components = { Child };
+      static template = xml`<div><Child/></div>`;
+    }
+
+    const w = new App(undefined, {});
+    let error;
+    try {
+      await w.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Missing props 'mandatory' (component 'Child')");
+  });
 });
 
 describe("default props", () => {
   test("can set default values", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Component {
       static defaultProps = { p: 4 };
       static template = xml`<div><t t-esc="props.p"/></div>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><TestWidget /></div>`;
       static components = { TestWidget };
     }

tests/component/styles.test.ts

@@ -0,0 +1,170 @@
+import { Component, Env } from "../../src/component/component";
+import { processSheet } from "../../src/component/styles";
+import { xml, css } from "../../src/tags";
+import { makeTestFixture, makeTestEnv } from "../helpers";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: an Env, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+  Component.env = env;
+  document.head.innerHTML = "";
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+describe("styles and component", () => {
+  test("can define an inline stylesheet", async () => {
+    class App extends Component {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+        }
+      `;
+    }
+    expect(document.head.innerHTML).toBe("");
+    const app = new App();
+
+    expect(document.head.innerHTML).toBe(`<style component=\"App\">.app {
+  color: red;
+}</style>`);
+
+    await app.mount(fixture);
+    const style = getComputedStyle(app.el!);
+    expect(style.color).toBe("red");
+    expect(fixture.innerHTML).toBe('<div class="app">text</div>');
+  });
+
+  test("inherited components properly apply css", async () => {
+    class App extends Component {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+        }
+      `;
+    }
+    class SubApp extends App {
+      static style = css`
+        .app {
+          font-weight: bold;
+        }
+      `;
+    }
+    expect(document.head.innerHTML).toBe("");
+    const app = new SubApp();
+
+    expect(document.head.innerHTML).toBe(`<style component=\"SubApp\">.app {
+  font-weight: bold;
+}</style><style component=\"App\">.app {
+  color: red;
+}</style>`);
+
+    await app.mount(fixture);
+    const style = getComputedStyle(app.el!);
+    expect(style.color).toBe("red");
+    expect(style.fontWeight).toBe("bold");
+    expect(fixture.innerHTML).toBe('<div class="app">text</div>');
+  });
+
+  test("get a meaningful error message if css helper is missing", async () => {
+    class App extends Component {
+      static template = xml`<div class="app">text</div>`;
+      static style = `.app {color: red;}`;
+    }
+    let error;
+    try {
+      new App();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe(
+      "Invalid css stylesheet for component 'App'. Did you forget to use the 'css' tag helper?"
+    );
+  });
+
+  test("inline stylesheets are processed", async () => {
+    class App extends Component {
+      static template = xml`<div class="app">text</div>`;
+      static style = css`
+        .app {
+          color: red;
+          .some-class {
+            font-weight: bold;
+            width: 40px;
+          }
+
+          display: block;
+        }
+      `;
+    }
+    new App();
+
+    expect(document.head.querySelector("style")!.innerHTML).toBe(`.app {
+  color: red;
+}
+.app .some-class {
+  font-weight: bold;
+  width: 40px;
+}
+.app {
+  display: block;
+}`);
+  });
+
+  test("properly handle rules with commas", async () => {
+    const sheet = processSheet(`.parent-a, .parent-b {
+      .child-a, .child-b {
+        color: red;
+      }
+    }`);
+
+    expect(sheet)
+      .toBe(`.parent-a .child-a, .parent-a .child-b, .parent-b .child-a, .parent-b .child-b {
+  color: red;
+}`);
+  });
+
+  test("handle & selector", async () => {
+    let sheet = processSheet(`.btn {
+      &.danger {
+        color: red;
+      }
+    }`);
+
+    expect(sheet).toBe(`.btn.danger {
+  color: red;
+}`);
+
+    sheet = processSheet(`.some-class {
+      &.btn {
+        .other-class ~ & {
+          color: red;
+        }
+      }
+    }`);
+
+    expect(sheet).toBe(`.other-class ~ .some-class.btn {
+  color: red;
+}`);
+  });
+});

tests/component/un_mounting.test.ts

@@ -0,0 +1,732 @@
+import { Component, Env, mount } from "../../src/component/component";
+import { useState } from "../../src/hooks";
+import { xml } from "../../src/tags";
+import { makeDeferred, makeTestEnv, makeTestFixture, nextTick, nextMicroTick } from "../helpers";
+import { scheduler } from "../../src/component/scheduler";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: a WEnv, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+  Component.env = env;
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("mount targets", () => {
+  test("can attach a component to an existing node (if same tagname)", async () => {
+    class App extends Component {
+      static template = xml`<div t-att-class="state.customClass">app<p>another tag</p></div>`;
+      state = useState({ customClass: "custom" });
+    }
+    const div = document.createElement("div");
+    div.classList.add("arbitrary");
+    div.innerHTML = `<p>pre-existing</p>`;
+    fixture.appendChild(div);
+
+    const app = await mount(App, { target: div, position: "self" });
+
+    expect(fixture.innerHTML).toBe(
+      `<div class="arbitrary custom"><p>pre-existing</p>app<p>another tag</p></div>`
+    );
+    expect(div).toBe(app.el);
+
+    app.state.customClass = "custom2";
+    await nextTick();
+    expect(fixture.innerHTML).toBe(
+      `<div class="arbitrary custom2"><p>pre-existing</p>app<p>another tag</p></div>`
+    );
+    expect(div).toBe(app.el);
+
+    app.unmount();
+    // This assert is a best guess
+    // The use case it covers was not really thought through
+    // and may change in the future
+    expect(fixture.innerHTML).toBe("");
+  });
+
+  test("cannot attach a component to an existing node (if not same tagname)", async () => {
+    class App extends Component {
+      static template = xml`<span>app</span>`;
+    }
+    const div = document.createElement("div");
+    fixture.appendChild(div);
+
+    let error;
+    try {
+      await mount(App, { target: div, position: "self" });
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Cannot attach 'App' to target node (not same tag name)");
+  });
+
+  test("can mount a component (with position='first-child')", async () => {
+    class App extends Component {
+      static template = xml`<div>app</div>`;
+    }
+    const span = document.createElement("span");
+    fixture.appendChild(span);
+
+    await mount(App, { target: fixture, position: "first-child" });
+    expect(fixture.innerHTML).toBe("<div>app</div><span></span>");
+  });
+
+  test("can mount a component (with position='last-child')", async () => {
+    class App extends Component {
+      static template = xml`<div>app</div>`;
+    }
+    const span = document.createElement("span");
+    fixture.appendChild(span);
+
+    await mount(App, { target: fixture, position: "last-child" });
+    expect(fixture.innerHTML).toBe("<span></span><div>app</div>");
+  });
+
+  test("default mount option is 'last-child'", async () => {
+    class App extends Component {
+      static template = xml`<div>app</div>`;
+    }
+    const span = document.createElement("span");
+    fixture.appendChild(span);
+
+    await mount(App, { target: fixture });
+    expect(fixture.innerHTML).toBe("<span></span><div>app</div>");
+  });
+});
+
+describe("unmounting and remounting", () => {
+  test("widget can be unmounted and remounted", async () => {
+    const steps: string[] = [];
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+      async willStart() {
+        steps.push("willstart");
+      }
+      mounted() {
+        steps.push("mounted");
+      }
+      willUnmount() {
+        steps.push("willunmount");
+      }
+      patched() {
+        throw new Error("patched should not be called");
+      }
+    }
+
+    const w = await mount(MyWidget, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div>Hey</div>");
+    expect(steps).toEqual(["willstart", "mounted"]);
+
+    w.unmount();
+    expect(fixture.innerHTML).toBe("");
+    expect(steps).toEqual(["willstart", "mounted", "willunmount"]);
+
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>Hey</div>");
+    expect(steps).toEqual(["willstart", "mounted", "willunmount", "mounted"]);
+  });
+
+  test("widget can be mounted twice without ill effect", async () => {
+    const steps: string[] = [];
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+      async willStart() {
+        steps.push("willstart");
+      }
+      mounted() {
+        steps.push("mounted");
+      }
+      willUnmount() {
+        steps.push("willunmount");
+      }
+    }
+
+    const w = await mount(MyWidget, { target: fixture });
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>Hey</div>");
+    expect(steps).toEqual(["willstart", "mounted"]);
+  });
+
+  test("state changes in willUnmount do not trigger rerender", async () => {
+    const steps: string[] = [];
+
+    class Child extends Component {
+      static template = xml`
+          <span><t t-esc="props.val"/><t t-esc="state.n"/></span>
+        `;
+      state = useState({ n: 2 });
+      __render(f) {
+        steps.push("render");
+        return super.__render(f);
+      }
+      willPatch() {
+        steps.push("willPatch");
+      }
+      patched() {
+        steps.push("patched");
+      }
+
+      willUnmount() {
+        steps.push("willUnmount");
+        this.state.n = 3;
+      }
+    }
+    class Parent extends Component {
+      static template = xml`
+          <div>
+            <Child t-if="state.flag" val="state.val"/>
+          </div>
+        `;
+      static components = { Child };
+      state = useState({ val: 1, flag: true });
+    }
+
+    const widget = await mount(Parent, { target: fixture });
+    expect(steps).toEqual(["render"]);
+    expect(fixture.innerHTML).toBe("<div><span>12</span></div>");
+    widget.state.flag = false;
+    await nextTick();
+    // we make sure here that no call to __render is done
+    expect(steps).toEqual(["render", "willUnmount"]);
+  });
+
+  test("state changes in willUnmount will be applied on remount", async () => {
+    class TestWidget extends Component {
+      static template = xml`
+          <div><t t-esc="state.val"/></div>
+        `;
+      state = useState({ val: 1 });
+      willUnmount() {
+        this.state.val = 3;
+      }
+    }
+
+    const widget = new TestWidget();
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>1</div>");
+    widget.unmount();
+    expect(fixture.innerHTML).toBe("");
+    await nextTick(); // wait for changes to be detected before remounting
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>3</div>");
+    // we want to make sure that there are no remaining tasks left at this point.
+    expect(Component.scheduler.tasks.length).toBe(0);
+  });
+
+  test("sub component is still active after being unmounted and remounted", async () => {
+    class Child extends Component {
+      static template = xml`
+          <p t-on-click="state.value++">
+            <t t-esc="state.value"/>
+          </p>`;
+
+      state = useState({ value: 1 });
+    }
+
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`<div><Child/></div>`;
+    }
+
+    const w = new Parent();
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><p>1</p></div>");
+
+    fixture.querySelector("p")!.click();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><p>2</p></div>");
+    w.unmount();
+    await nextTick();
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><p>2</p></div>");
+    fixture.querySelector("p")!.click();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><p>3</p></div>");
+  });
+
+  test("change state just before mounting component", async () => {
+    const steps: number[] = [];
+    class TestWidget extends Component {
+      static template = xml`
+          <div><t t-esc="state.val"/></div>
+        `;
+      state = useState({ val: 1 });
+      __render(f) {
+        steps.push(this.state.val);
+        return super.__render(f);
+      }
+    }
+    TestWidget.prototype.__render = jest.fn(TestWidget.prototype.__render);
+
+    const widget = new TestWidget();
+    widget.state.val = 2;
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>2</div>");
+    expect(TestWidget.prototype.__render).toHaveBeenCalledTimes(1);
+
+    // unmount and re-mount, as in this case, willStart won't be called, so it's
+    // slightly different
+    widget.unmount();
+    widget.state.val = 3;
+    await widget.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>3</div>");
+    expect(TestWidget.prototype.__render).toHaveBeenCalledTimes(2);
+    expect(steps).toEqual([2, 3]);
+  });
+
+  test("change state while mounting component", async () => {
+    const steps: number[] = [];
+    class TestWidget extends Component {
+      static template = xml`
+          <div><t t-esc="state.val"/></div>
+        `;
+      state = useState({ val: 1 });
+      __render(f) {
+        steps.push(this.state.val);
+        return super.__render(f);
+      }
+    }
+    TestWidget.prototype.__render = jest.fn(TestWidget.prototype.__render);
+    TestWidget.prototype.__patch = jest.fn(TestWidget.prototype.__patch);
+
+    const widget = new TestWidget();
+    let prom = widget.mount(fixture);
+    widget.state.val = 2;
+    await prom;
+    expect(fixture.innerHTML).toBe("<div>2</div>");
+    expect(TestWidget.prototype.__render).toHaveBeenCalledTimes(1);
+
+    // unmount and re-mount, as in this case, willStart won't be called, so it's
+    // slightly different
+    widget.unmount();
+    prom = widget.mount(fixture);
+    widget.state.val = 3;
+    await prom;
+    expect(fixture.innerHTML).toBe("<div>3</div>");
+    expect(TestWidget.prototype.__render).toHaveBeenCalledTimes(3);
+    expect(TestWidget.prototype.__patch).toHaveBeenCalledTimes(2);
+    expect(steps).toEqual([2, 2, 3]);
+  });
+
+  test("change state and render while mounted in detached dom", async () => {
+    class App extends Component {
+      static template = xml`<div><t t-esc="state.val"/></div>`;
+      state = useState({ val: 1 });
+    }
+
+    const detachedDiv = document.createElement("div");
+    const app = await mount(App, { target: detachedDiv });
+
+    expect(detachedDiv.innerHTML).toBe("<div>1</div>");
+    app.state.val = 2;
+    await nextTick();
+    expect(detachedDiv.innerHTML).toBe("<div>2</div>");
+  });
+
+  test("change state and render while not mounted ", async () => {
+    class App extends Component {
+      static template = xml`<div><t t-esc="state.val"/></div>`;
+      state = useState({ val: 1 });
+    }
+
+    const app = new App(null);
+
+    app.state.val = 2; // will call the render method (before being mounted)
+    await nextTick();
+
+    await app.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div>2</div>");
+  });
+
+  test("destroy and change state after mounted in detached dom", async () => {
+    class App extends Component {
+      static template = xml`<div><t t-esc="state.val"/></div>`;
+      state = useState({ val: 1 });
+    }
+
+    const detachedDiv = document.createElement("div");
+    const app = await mount(App, { target: detachedDiv });
+
+    expect(detachedDiv.innerHTML).toBe("<div>1</div>");
+
+    app.destroy();
+    app.state.val = 2;
+    await nextTick();
+    expect(detachedDiv.innerHTML).toBe("");
+  });
+
+  test("change state while component is unmounted", async () => {
+    let child;
+    class Child extends Component {
+      static template = xml`<span t-esc="state.val"/>`;
+      state = useState({
+        val: "C1",
+      });
+      constructor(parent, props) {
+        super(parent, props);
+        child = this;
+      }
+    }
+
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`<div><t t-esc="state.val"/><Child/></div>`;
+      state = useState({ val: "P1" });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>P1<span>C1</span></div>");
+
+    parent.unmount();
+    expect(fixture.innerHTML).toBe("");
+
+    parent.state.val = "P2";
+    child.state.val = "C2";
+
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>P2<span>C2</span></div>");
+  });
+
+  test("change state while component is mounted in a fragment", async () => {
+    class Child1 extends Component {
+      static template = xml`<span>C1</span>`;
+    }
+
+    class Child2 extends Component {
+      static template = xml`<span>C2</span>`;
+    }
+
+    class Parent extends Component {
+      static components = { Child1, Child2 };
+      static template = xml`
+        <div>
+          <Child1 t-if="child == 'c1'"/>
+          <Child2 t-if="child == 'c2'"/>
+        </div>`;
+      child: string | false = false;
+    }
+
+    const fragment = document.createDocumentFragment();
+    const parent = new Parent();
+    await parent.mount(fragment);
+    expect(parent.el.outerHTML).toBe("<div></div>");
+
+    parent.child = "c1";
+    parent.render();
+    await Promise.resolve();
+
+    parent.child = "c2";
+    await parent.mount(fixture);
+
+    expect(fixture.innerHTML).toBe("<div><span>C2</span></div>");
+  });
+
+  test("unmount component during a re-rendering", async () => {
+    const def = makeDeferred();
+    class Child extends Component {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+      willUpdateProps() {
+        return def;
+      }
+    }
+    Child.prototype.__render = jest.fn(Child.prototype.__render);
+
+    class Parent extends Component {
+      static template = xml`<div><Child val="state.val"/></div>`;
+      static components = { Child };
+      state = useState({ val: 1 });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><span>1</span></div>");
+    expect(Child.prototype.__render).toBeCalledTimes(1);
+
+    parent.state.val = 2;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>1</span></div>");
+
+    parent.unmount();
+    expect(fixture.innerHTML).toBe("");
+
+    def.resolve();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("");
+    expect(Child.prototype.__render).toBeCalledTimes(1);
+  });
+
+  test("widget can be mounted on different target", async () => {
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+      patched() {
+        throw new Error("patched should not be called");
+      }
+    }
+    const div = document.createElement("div");
+    const span = document.createElement("span");
+    fixture.appendChild(div);
+    fixture.appendChild(span);
+    const w = new MyWidget();
+    await w.mount(div);
+
+    expect(fixture.innerHTML).toBe("<div><div>Hey</div></div><span></span>");
+
+    await w.mount(span);
+    expect(fixture.innerHTML).toBe("<div></div><span><div>Hey</div></span>");
+  });
+
+  test("widget can be mounted on different target, another situation", async () => {
+    const def = makeDeferred();
+    const steps: string[] = [];
+
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+      async willStart() {
+        return def;
+      }
+      patched() {
+        throw new Error("patched should not be called");
+      }
+    }
+    const div = document.createElement("div");
+    const span = document.createElement("span");
+    fixture.appendChild(div);
+    fixture.appendChild(span);
+    const w = new MyWidget();
+
+    w.mount(div).catch(() => steps.push("1 catch"));
+
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div></div><span></span>");
+
+    w.mount(span).then(() => steps.push("2 resolved"));
+
+    // we wait two microticks because this is the number of internal promises
+    // that need to be resolved/rejected, and because we want to prove here
+    // that the first mount operation is cancelled immediately, and not after
+    // one full tick.
+    await nextMicroTick();
+    await nextMicroTick();
+    expect(steps).toEqual([]);
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div></div><span></span>");
+
+    def.resolve();
+    await nextTick();
+    expect(steps).toEqual(["2 resolved"]);
+    expect(fixture.innerHTML).toBe("<div></div><span><div>Hey</div></span>");
+  });
+
+  test("component can be mounted on same target, another situation", async () => {
+    const def = makeDeferred();
+    const steps: string[] = [];
+
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+      async willStart() {
+        return def;
+      }
+      patched() {
+        throw new Error("patched should not be called");
+      }
+    }
+    const w = new MyWidget();
+
+    w.mount(fixture).then(() => steps.push("1 resolved"));
+
+    await nextTick();
+    expect(fixture.innerHTML).toBe("");
+
+    w.mount(fixture).then(() => steps.push("2 resolved"));
+
+    await nextTick();
+    expect(steps).toEqual([]);
+    expect(fixture.innerHTML).toBe("");
+
+    def.resolve();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div>Hey</div>");
+    expect(steps).toEqual(["1 resolved", "2 resolved"]);
+  });
+
+  test("mounting a destroyed widget", async () => {
+    class MyWidget extends Component {
+      static template = xml`<div>Hey</div>`;
+    }
+    const w = new MyWidget();
+    w.destroy(); // because, why not
+
+    let error;
+    try {
+      await w.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(scheduler.tasks.length).toBe(0);
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Cannot mount a destroyed component");
+  });
+
+  test("destroying a sub-component cleans itself from parent's vnode", async () => {
+    class C1 extends Component {
+      static template = xml`<div><div><t t-esc="props.a"/></div></div>`;
+    }
+    class P extends Component {
+      static components = { C1 };
+      static template = xml`<div><div><C1 t-props="state" t-if="state.a"/></div></div>`;
+      state = {
+        a: "first",
+      };
+    }
+    const parent = new P();
+    await parent.mount(fixture);
+    expect(fixture.textContent).toBe("first");
+    parent.unmount();
+    parent.state.a = "";
+    parent.mount(fixture);
+    parent.state.a = "fixed";
+    await parent.render();
+    expect(fixture.textContent).toBe("fixed");
+  });
+
+  test("destroying a sub-component cleans itself from parent's vnode, part 2", async () => {
+    class C1 extends Component {
+      static template = xml`<div><div><t t-esc="props.a"/></div></div>`;
+    }
+    class P extends Component {
+      static components = { C1 };
+      static template = xml`<div><div><C1 t-props="state" t-if="state.a"/>some text</div></div>`;
+      state = {
+        a: "first",
+      };
+    }
+    const parent = new P();
+    await parent.mount(fixture);
+    expect(fixture.textContent).toBe("firstsome text");
+    parent.unmount();
+    parent.state.a = "";
+    parent.mount(fixture);
+    parent.state.a = "fixed";
+    await parent.render();
+    expect(fixture.textContent).toBe("fixedsome text");
+  });
+
+  test("destroying a sub-component cleans itself from parent's vnode, part 3", async () => {
+    class C1 extends Component {
+      static template = xml`<div><div><t t-esc="props.a"/></div></div>`;
+    }
+
+    class C2 extends Component {
+      static template = xml`<C1 a="props.a"/>`;
+      static components = { C1 };
+    }
+
+    class P extends Component {
+      static components = { C2 };
+      static template = xml`<div><div><C2 t-props="state" t-if="state.a"/></div></div>`;
+      state = {
+        a: "first",
+      };
+    }
+    const parent = new P();
+    await parent.mount(fixture);
+    expect(fixture.textContent).toBe("first");
+    parent.unmount();
+    parent.state.a = "";
+    parent.mount(fixture);
+    parent.state.a = "fixed";
+    await parent.render();
+    expect(fixture.textContent).toBe("fixed");
+  });
+
+  test("destroying a sub-component cleans itself from parent's vnode, part 4", async () => {
+    class C1 extends Component {
+      static template = xml`<div><div><t t-esc="props.a"/></div></div>`;
+    }
+
+    class C2 extends Component {
+      static template = xml`<C1 a="props.a"/>`;
+      static components = { C1 };
+    }
+    class P extends Component {
+      static components = { C2 };
+      static template = xml`<div><div><C2 t-props="state" t-if="state.a"/>some text</div></div>`;
+      state = {
+        a: "first",
+      };
+    }
+    const parent = new P();
+    await parent.mount(fixture);
+    expect(fixture.textContent).toBe("firstsome text");
+    parent.unmount();
+    parent.state.a = "";
+    parent.mount(fixture);
+    parent.state.a = "fixed";
+    await parent.render();
+    expect(fixture.textContent).toBe("fixedsome text");
+  });
+
+  test("remounting component tree where a component implement shouldupdate", async () => {
+    let state: any;
+    const steps = [];
+    class Child extends Component {
+      static template = xml`<div><t t-esc="state.word"/><t t-esc="props.name"/></div>`;
+
+      state = useState({ word: "hello" });
+
+      constructor(parent, props) {
+        super(parent, props);
+        state = this.state;
+      }
+      patched() {
+        steps.push("patched");
+      }
+      mounted() {
+        steps.push("mounted");
+      }
+      willUnmount() {
+        steps.push("willUnmount");
+      }
+      shouldUpdate() {
+        return false;
+      }
+    }
+
+    class Parent extends Component {
+      static template = xml`<div><Child name="state.name"/></div>`;
+      static components = { Child };
+      state = useState({ name: "World" });
+    }
+
+    const parent = await mount(Parent, { target: fixture });
+    expect(fixture.innerHTML).toBe("<div><div>helloWorld</div></div>");
+
+    parent.unmount();
+    expect(fixture.innerHTML).toBe("");
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>helloWorld</div></div>");
+
+    state.word = "test";
+
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><div>testWorld</div></div>");
+    expect(steps).toEqual(["mounted", "willUnmount", "mounted", "patched"]);
+  });
+});

tests/context.test.ts

@@ -32,7 +32,7 @@ describe("Context", () => {
   test("very simple use, with initial value", async () => {
     const testContext = new Context({ value: 123 });
 
-    class Test extends Component<any, any> {
+    class Test extends Component {
       static template = xml`<div><t t-esc="contextObj.value"/></div>`;
       contextObj = useContext(testContext);
     }
@@ -44,7 +44,7 @@ describe("Context", () => {
   test("useContext hook is reactive, for one component", async () => {
     const testContext = new Context({ value: 123 });
 
-    class Test extends Component<any, any> {
+    class Test extends Component {
       static template = xml`<div><t t-esc="contextObj.value"/></div>`;
       contextObj = useContext(testContext);
     }
@@ -59,11 +59,11 @@ describe("Context", () => {
   test("two components can subscribe to same context", async () => {
     const testContext = new Context({ value: 123 });
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj.value"/></span>`;
       contextObj = useContext(testContext);
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child /><Child /></div>`;
       static components = { Child };
     }
@@ -80,7 +80,7 @@ describe("Context", () => {
     const def = makeDeferred();
     const steps: string[] = [];
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj.value"/></span>`;
       contextObj = useContext(testContext);
       async render() {
@@ -90,7 +90,7 @@ describe("Context", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child /><Child /></div>`;
       static components = { Child };
     }
@@ -111,13 +111,13 @@ describe("Context", () => {
     const def = makeDeferred();
     const steps: string[] = [];
 
-    class SlowComp extends Component<any, any> {
+    class SlowComp extends Component {
       static template = xml`<p><t t-esc="props.value"/></p>`;
       willUpdateProps() {
         return def;
       }
     }
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><SlowComp value="contextObj.value"/></span>`;
       static components = { SlowComp };
       contextObj = useContext(testContext);
@@ -128,12 +128,12 @@ describe("Context", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child /><Child /></div>`;
       static components = { Child };
     }
 
-    class App extends Component<any, any> {
+    class App extends Component {
       static template = xml`<div><Child /><Parent /></div>`;
       static components = { Child, Parent };
     }
@@ -166,7 +166,7 @@ describe("Context", () => {
     const testContext = new Context({ a: 1, b: 2 });
     const steps: string[] = [];
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj1.a"/><t t-esc="contextObj2.b"/></span>`;
       contextObj1 = useContext(testContext);
       contextObj2 = useContext(testContext);
@@ -175,7 +175,7 @@ describe("Context", () => {
         return super.__render(fiber);
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child /></div>`;
       static components = { Child };
     }
@@ -193,7 +193,7 @@ describe("Context", () => {
     const testContext = new Context({ a: 123, b: 321 });
     const steps: string[] = [];
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj.a"/></span>`;
       contextObj = useContext(testContext);
       __render(fiber) {
@@ -201,7 +201,7 @@ describe("Context", () => {
         return super.__render(fiber);
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child /><t t-esc="contextObj.b"/></div>`;
       static components = { Child };
       contextObj = useContext(testContext);
@@ -227,7 +227,7 @@ describe("Context", () => {
     const testContext = new Context({ a: 123 });
     const steps: string[] = [];
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj.a"/></span>`;
       contextObj = useContext(testContext);
       __render(fiber) {
@@ -235,7 +235,7 @@ describe("Context", () => {
         return super.__render(fiber);
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child t-if="state.flag"/></div>`;
       static components = { Child };
       state = useState({ flag: true });
@@ -263,14 +263,14 @@ describe("Context", () => {
   test("destroyed component before being mounted is inactive", async () => {
     const testContext = new Context({ a: 123 });
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="contextObj.a"/></span>`;
       contextObj = useContext(testContext);
       willStart() {
         return makeDeferred();
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><Child t-if="state.flag"/></div>`;
       static components = { Child };
       state = useState({ flag: true });
@@ -289,11 +289,30 @@ describe("Context", () => {
     expect(testContext.subscriptions.update.length).toBe(0);
   });
 
-  test("concurrent renderings", async () => {
+  test.skip("concurrent renderings", async () => {
+    /**
+     * Note: this test is interesting, but sadly just an incomplete attempt at
+     * protecting users against themselves.  With the context API, it is not
+     * possible for the framework to protect completely against crashes.  Maybe
+     * like in this case, when a component is in a simple hierarchy where all
+     * renderings come from the context changes, but in a real case, where some
+     * code can trigger a rendering independently, it is insufficient.
+     *
+     * The main problem is that the sub component depends on some external state,
+     * which may be modified, and then incompatible with the component actual
+     * state (for example, if the sub component has an id key related to some
+     * object that has been removed from the context).
+     *
+     * For now, sadly, the only solution is that components that depends on external
+     * state should guarantee their own integrity themselves. Then maybe this
+     * could be solved at the level of a state management solution that has a
+     * more advanced API, to let components determine if they should be updated
+     * or not (so, something slightly more advanced that the useStore hook).
+     */
     const testContext = new Context({ x: { n: 1 }, key: "x" });
     const def = makeDeferred();
     let stateC;
-    class ComponentC extends Component<any, any> {
+    class ComponentC extends Component {
       static template = xml`<span><t t-esc="context[props.key].n"/><t t-esc="state.x"/></span>`;
       context = useContext(testContext);
       state = useState({ x: "a" });
@@ -303,7 +322,7 @@ describe("Context", () => {
         stateC = this.state;
       }
     }
-    class ComponentB extends Component<any, any> {
+    class ComponentB extends Component {
       static components = { ComponentC };
       static template = xml`<p><ComponentC key="props.key"/></p>`;
 
@@ -311,7 +330,7 @@ describe("Context", () => {
         return def;
       }
     }
-    class ComponentA extends Component<any, any> {
+    class ComponentA extends Component {
       static components = { ComponentB };
       static template = xml`<div><ComponentB key="context.key"/></div>`;
       context = useContext(testContext);

tests/core/event_bus.test.ts

@@ -14,7 +14,7 @@ describe("event bus behaviour", () => {
     expect.assertions(1);
     const bus = new EventBus();
     const owner = {};
-    bus.on("event", owner, function(this: any) {
+    bus.on("event", owner, function (this: any) {
       expect(this).toBe(owner);
     });
     bus.trigger("event");

tests/core/observer.test.ts

@@ -22,7 +22,7 @@ describe("observer", () => {
     expect(observer.rev).toBe(2);
 
     expect(obj2).toEqual({
-      a: 2
+      a: 2,
     });
   });
 
@@ -47,7 +47,7 @@ describe("observer", () => {
     expect(observer.rev).toBe(5);
     expect(obj).toEqual({
       a: null,
-      b: undefined
+      b: undefined,
     });
   });
 
@@ -68,6 +68,23 @@ describe("observer", () => {
     expect(obj.date).not.toBe(date);
   });
 
+  test("properly handle promises (i.e.: treat them like primitive values", async () => {
+    const observer = new Observer();
+    let resolved = false;
+    const prom = new Promise((r) => r());
+    const obj: any = observer.observe({ prom });
+    expect(obj.prom).toBeInstanceOf(Promise);
+
+    obj.prom.then(() => (resolved = true));
+
+    expect(observer.revNumber(obj)).toBe(1);
+
+    expect(resolved).toBe(false);
+    await Promise.resolve();
+    expect(resolved).toBe(true);
+    expect(observer.revNumber(obj)).toBe(1);
+  });
+
   test("can change values in array", () => {
     const observer = new Observer();
     const obj: any = observer.observe({ arr: [1, 2] });
@@ -429,44 +446,4 @@ describe("observer", () => {
       obj.a.push(2);
     }).toThrow('Observed state cannot be changed here! (key: "1", val: "2")');
   });
-
-  test("functions are not observed, but are properly bound", () => {
-    const observer = new Observer();
-    const obj: any = observer.observe({ m: new Map() });
-    expect(observer.rev).toBe(1);
-    obj.m.set("a", 1);
-    expect(obj.m.get("a")).toBe(1);
-
-    // should be 2, but we do not support reactivity on maps/weakmaps/set/weakset
-    expect(observer.rev).toBe(1);
-  });
-
-  test("functions are correctly bound", async () => {
-    const observer = new Observer();
-    const obj: any = observer.observe({ set: new Set() });
-    expect(observer.revNumber(obj)).toBe(1);
-    obj.set.add('mojo');
-    expect(observer.revNumber(obj)).toBe(1);
-
-    const steps: string[] = [];
-    obj.set.forEach((elm)=>{steps.push(elm)});
-
-    expect(steps).toStrictEqual(['mojo']);
-
-    obj.set.clear();
-    expect(observer.revNumber(obj)).toBe(1);
-  });
-
-  test("functions are correctly bound", async () => {
-    const observer = new Observer();
-    const obj: any = observer.observe({ set: [] });
-    expect(observer.revNumber(obj)).toBe(1);
-    obj.set.push('mojo');
-    expect(observer.revNumber(obj)).toBe(2);
-
-    const steps: string[] = [];
-    obj.set.forEach((elm)=>{steps.push(elm)});
-
-    expect(steps).toStrictEqual(['mojo']);
-  });
 });

tests/helpers.ts

@@ -1,4 +1,4 @@
-import { Env, Component } from "../src/component/component";
+import { Env, Component, STATUS } from "../src/component/component";
 import { scheduler } from "../src/component/scheduler";
 import { EvalContext, QWeb } from "../src/qweb/qweb";
 import { CompilationContext } from "../src/qweb/compilation_context";
@@ -6,12 +6,7 @@ import { patch } from "../src/vdom";
 import "../src/qweb/base_directives";
 import "../src/qweb/extensions";
 import "../src/component/directive";
-
-// modifies scheduler to make it faster to test components
-scheduler.requestAnimationFrame = function(callback: FrameRequestCallback) {
-  setTimeout(callback, 1);
-  return 1;
-};
+import { browser } from "../src/browser";
 
 // Some static cleanup
 let nextSlotId;
@@ -42,9 +37,13 @@ export function nextMicroTick(): Promise<void> {
 }
 
 export async function nextTick(): Promise<void> {
-  return new Promise(function(resolve) {
-    setTimeout(() => scheduler.requestAnimationFrame(() => resolve()));
-  });
+  await new Promise((resolve) => setTimeout(resolve));
+  await new Promise((resolve) => scheduler.requestAnimationFrame(resolve));
+}
+
+export async function nextFrame(): Promise<void> {
+  await new Promise((resolve) => scheduler.requestAnimationFrame(resolve));
+  await new Promise((resolve) => scheduler.requestAnimationFrame(resolve));
 }
 
 export function makeTestFixture() {
@@ -75,7 +74,8 @@ export function makeDeferred(): Deferred {
 
 export function makeTestEnv(): Env {
   return {
-    qweb: new QWeb()
+    qweb: new QWeb(),
+    browser: browser,
   };
 }
 
@@ -92,7 +92,7 @@ export function renderToDOM(
   if (!context.__owl__) {
     // we add `__owl__` to better simulate a component as context.  This is
     // particularly important for event handlers added with the `t-on` directive.
-    context.__owl__ = { isMounted: true };
+    context.__owl__ = { status: STATUS.MOUNTED };
   }
   const vnode = qweb.render(template, context, extra);
 
@@ -132,7 +132,7 @@ export function renderToString(
 // is useful for animations tests, as we hook before repaints to trigger
 // animations (thanks to requestAnimationFrame). Patching nextFrame allows to
 // simulate calls to this hook. One must not forget to unpatch afterwards.
-let nextFrame = QWeb.utils.nextFrame;
+let _nextFrame = QWeb.utils.nextFrame;
 export function patchNextFrame(f: Function) {
   QWeb.utils.nextFrame = (cb: () => void) => {
     setTimeout(() => f(cb));
@@ -140,7 +140,7 @@ export function patchNextFrame(f: Function) {
 }
 
 export function unpatchNextFrame() {
-  QWeb.utils.nextFrame = nextFrame;
+  QWeb.utils.nextFrame = _nextFrame;
 }
 
 export async function editInput(input: HTMLInputElement | HTMLTextAreaElement, value: string) {

tests/hooks.test.ts

@@ -9,7 +9,10 @@ import {
   onWillPatch,
   onWillStart,
   onWillUpdateProps,
-  useSubEnv
+  useEnv,
+  useSubEnv,
+  useExternalListener,
+  useComponent,
 } from "../src/hooks";
 import { xml } from "../src/tags";
 
@@ -41,7 +44,7 @@ afterEach(() => {
 
 describe("hooks", () => {
   test("can use a state hook", async () => {
-    class Counter extends Component<any, any> {
+    class Counter extends Component {
       static template = xml`<div><t t-esc="counter.value"/></div>`;
       counter = useState({ value: 42 });
     }
@@ -63,7 +66,7 @@ describe("hooks", () => {
         steps.push("willunmount");
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey</div>`;
       constructor() {
         super();
@@ -72,8 +75,6 @@ describe("hooks", () => {
     }
     const component = new MyComponent();
     await component.mount(fixture);
-    expect(component).not.toHaveProperty("mounted");
-    expect(component).not.toHaveProperty("willUnmount");
     expect(fixture.innerHTML).toBe("<div>hey</div>");
     expect(steps).toEqual(["mounted"]);
     component.unmount();
@@ -91,7 +92,7 @@ describe("hooks", () => {
         steps.push("willunmount");
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey</div>`;
       constructor(parent, props) {
         super(parent, props);
@@ -99,7 +100,7 @@ describe("hooks", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
       static components = { MyComponent };
       state = useState({ flag: true });
@@ -125,7 +126,7 @@ describe("hooks", () => {
         steps.push("hook:willunmount");
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey</div>`;
       constructor() {
         super();
@@ -156,7 +157,7 @@ describe("hooks", () => {
         steps.push("hook:willunmount");
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey</div>`;
       constructor(parent, props) {
         super(parent, props);
@@ -170,7 +171,7 @@ describe("hooks", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
       static components = { MyComponent };
       state = useState({ flag: true });
@@ -196,7 +197,7 @@ describe("hooks", () => {
         steps.push("hook:willunmount" + i);
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey</div>`;
       constructor() {
         super();
@@ -213,12 +214,12 @@ describe("hooks", () => {
       "hook:mounted1",
       "hook:mounted2",
       "hook:willunmount2",
-      "hook:willunmount1"
+      "hook:willunmount1",
     ]);
   });
 
   test("useRef hook", async () => {
-    class Counter extends Component<any, any> {
+    class Counter extends Component {
       static template = xml`<div><button t-ref="button"><t t-esc="value"/></button></div>`;
       button = useRef("button");
       value = 0;
@@ -240,7 +241,7 @@ describe("hooks", () => {
 
   test("useRef hook is null if ref is removed ", async () => {
     expect.assertions(4);
-    class TestRef extends Component<any, any> {
+    class TestRef extends Component {
       static template = xml`<div><span t-if="state.flag" t-ref="span">owl</span></div>`;
       spanRef = useRef("span");
       state = useState({ flag: true });
@@ -260,13 +261,13 @@ describe("hooks", () => {
   });
 
   test("t-refs on widget are components", async () => {
-    class WidgetB extends Component<any, any> {
+    class WidgetB extends Component {
       static template = xml`<div>b</div>`;
     }
-    class WidgetC extends Component<any, any> {
+    class WidgetC extends Component {
       static template = xml`<div class="outer-div">Hello<WidgetB t-ref="mywidgetb" /></div>`;
       static components = { WidgetB };
-      ref = useRef("mywidgetb");
+      ref = useRef<WidgetB>("mywidgetb");
     }
 
     const widget = new WidgetC();
@@ -279,11 +280,11 @@ describe("hooks", () => {
 
   test("t-refs are bound at proper timing", async () => {
     expect.assertions(2);
-    class Widget extends Component<any, any> {
+    class Widget extends Component {
       static template = xml`<div>widget</div>`;
     }
 
-    class ParentWidget extends Component<any, any> {
+    class ParentWidget extends Component {
       static template = xml`
         <div>
           <t t-foreach="state.list" t-as="elem" t-ref="child" t-key="elem" t-component="Widget"/>
@@ -308,10 +309,10 @@ describe("hooks", () => {
 
   test("t-refs are bound at proper timing (2)", async () => {
     expect.assertions(10);
-    class Widget extends Component<any, any> {
+    class Widget extends Component {
       static template = xml`<div>widget</div>`;
     }
-    class ParentWidget extends Component<any, any> {
+    class ParentWidget extends Component {
       static template = xml`
         <div>
           <t t-if="state.child1" t-ref="child1" t-component="Widget"/>
@@ -368,7 +369,7 @@ describe("hooks", () => {
       });
     }
 
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div><t t-if="state.flag">hey</t></div>`;
       state = useState({ flag: true });
 
@@ -380,8 +381,6 @@ describe("hooks", () => {
 
     const component = new MyComponent();
     await component.mount(fixture);
-    expect(component).not.toHaveProperty("patched");
-    expect(component).not.toHaveProperty("willPatch");
     expect(steps).toEqual([]);
 
     expect(fixture.innerHTML).toBe("<div>hey</div>");
@@ -402,7 +401,7 @@ describe("hooks", () => {
         steps.push("hook:willPatch");
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div><t t-if="state.flag">hey</t></div>`;
       state = useState({ flag: true });
 
@@ -436,7 +435,7 @@ describe("hooks", () => {
         steps.push("hook:willPatch" + i);
       });
     }
-    class MyComponent extends Component<any, any> {
+    class MyComponent extends Component {
       static template = xml`<div>hey<t t-esc="state.value"/></div>`;
       state = useState({ value: 1 });
       constructor() {
@@ -472,7 +471,7 @@ describe("hooks", () => {
     }
 
     test("simple input", async () => {
-      class SomeComponent extends Component<any, any> {
+      class SomeComponent extends Component {
         static template = xml`
             <div>
                 <input t-ref="input1"/>
@@ -493,7 +492,7 @@ describe("hooks", () => {
     });
 
     test("input in a t-if", async () => {
-      class SomeComponent extends Component<any, any> {
+      class SomeComponent extends Component {
         static template = xml`
             <div>
                 <input t-ref="input1"/>
@@ -519,8 +518,21 @@ describe("hooks", () => {
     });
   });
 
+  test("can use useEnv", async () => {
+    expect.assertions(1);
+    class TestComponent extends Component {
+      static template = xml`<div><t t-esc="env.val"/></div>`;
+      constructor() {
+        super();
+        expect(useEnv()).toBe(env);
+      }
+    }
+    const component = new TestComponent();
+    await component.mount(fixture);
+  });
+
   test("can use sub env", async () => {
-    class TestComponent extends Component<any, any> {
+    class TestComponent extends Component {
       static template = xml`<div><t t-esc="env.val"/></div>`;
       constructor() {
         super();
@@ -534,8 +546,21 @@ describe("hooks", () => {
     expect(component.env).toHaveProperty("val");
   });
 
+  test("can use useComponent", async () => {
+    expect.assertions(1);
+    class TestComponent extends Component {
+      static template = xml`<div></div>`;
+      constructor() {
+        super();
+        expect(useComponent()).toBe(this);
+      }
+    }
+    const component = new TestComponent();
+    await component.mount(fixture);
+  });
+
   test("parent and child env", async () => {
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<div><t t-esc="env.val"/></div>`;
       constructor(parent, props) {
         super(parent, props);
@@ -543,7 +568,7 @@ describe("hooks", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`<div><t t-esc="env.val"/><Child/></div>`;
       static components = { Child };
       constructor() {
@@ -558,23 +583,42 @@ describe("hooks", () => {
 
   test("can use onWillStart, onWillUpdateProps", async () => {
     const steps: string[] = [];
+    async function slow(): Promise<string> {
+      return new Promise((resolve) => {
+        setTimeout(() => {
+          resolve("slow");
+        }, 0);
+      });
+    }
     function useMyHook() {
-      onWillStart(() => {
+      onWillStart(async () => {
+        steps.push(await slow());
         steps.push("onWillStart");
       });
-      onWillUpdateProps(nextProps => {
+      onWillUpdateProps(async (nextProps) => {
         expect(nextProps).toEqual({ value: 2 });
+        steps.push(await slow());
         steps.push("onWillUpdateProps");
       });
     }
-    class MyComponent extends Component<any, any> {
+    function use2ndHook() {
+      onWillStart(() => {
+        steps.push("on2ndStart");
+      });
+      onWillUpdateProps((nextProps) => {
+        expect(nextProps).toEqual({ value: 2 });
+        steps.push("on2ndUpdate");
+      });
+    }
+    class MyComponent extends Component {
       static template = xml`<span><t t-esc="props.value"/></span>`;
       constructor(parent, props) {
         super(parent, props);
         useMyHook();
+        use2ndHook();
       }
     }
-    class App extends Component<any, any> {
+    class App extends Component {
       static template = xml`<div><MyComponent value="state.value"/></div>`;
       static components = { MyComponent };
       state = useState({ value: 1 });
@@ -582,14 +626,61 @@ describe("hooks", () => {
 
     const app = new App();
     await app.mount(fixture);
-    expect(app).not.toHaveProperty("willStart");
-    expect(app).not.toHaveProperty("willUpdateProps");
     expect(fixture.innerHTML).toBe("<div><span>1</span></div>");
-    expect(steps).toEqual(["onWillStart"]);
+
+    // NOTE: 'on2ndStart' appears first in the list even though
+    // the 'use2ndHook' is declared after 'useMyHook'. This is
+    // because Promise.all is used to call the callbacks specified
+    // in the hooks, which runs them simultaneously.
+    // Additionally, 'slow' should be listed before 'onWillStart'
+    // because call to `slow` is awaited.
+    expect(steps).toEqual(["on2ndStart", "slow", "onWillStart"]);
 
     app.state.value = 2;
     await nextTick();
     expect(fixture.innerHTML).toBe("<div><span>2</span></div>");
-    expect(steps).toEqual(["onWillStart", "onWillUpdateProps"]);
+    expect(steps).toEqual([
+      "on2ndStart",
+      "slow",
+      "onWillStart",
+      "on2ndUpdate",
+      "slow",
+      "onWillUpdateProps",
+    ]);
+  });
+
+  test("useExternalListener", async () => {
+    let n = 0;
+
+    class MyComponent extends Component {
+      static template = xml`<span><t t-esc="props.value"/></span>`;
+      constructor(parent, props) {
+        super(parent, props);
+        useExternalListener(window as any, "click", this.increment);
+      }
+      increment() {
+        n++;
+      }
+    }
+    class App extends Component {
+      static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
+      static components = { MyComponent };
+      state = useState({ flag: false });
+    }
+
+    const app = new App();
+    await app.mount(fixture);
+
+    expect(n).toBe(0);
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(0);
+    app.state.flag = true;
+    await nextTick();
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(1);
+    app.state.flag = false;
+    await nextTick();
+    window.dispatchEvent(new Event("click"));
+    expect(n).toBe(1);
   });
 });

tests/misc/async_root.test.ts

@@ -27,7 +27,7 @@ afterEach(() => {
 describe("Asyncroot", () => {
   test("delayed component with AsyncRoot component", async () => {
     let def;
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="props.val"/></span>`;
     }
     class AsyncChild extends Child {
@@ -35,7 +35,7 @@ describe("Asyncroot", () => {
         return def;
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`
           <div>
             <button t-on-click="updateApp">Update App State</button>
@@ -74,7 +74,7 @@ describe("Asyncroot", () => {
 
   test("fast component with AsyncRoot", async () => {
     let def;
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="props.val"/></span>`;
     }
     class AsyncChild extends Child {
@@ -83,7 +83,7 @@ describe("Asyncroot", () => {
       }
     }
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`
           <div>
             <button t-on-click="updateApp">Update App State</button>
@@ -122,7 +122,7 @@ describe("Asyncroot", () => {
 
   test("asyncroot component: mixed re-renderings", async () => {
     let def;
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`
         <span t-on-click="increment">
           <t t-esc="state.val"/>/<t t-esc="props.val"/>
@@ -138,7 +138,7 @@ describe("Asyncroot", () => {
         return def;
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static template = xml`
         <div>
           <button t-on-click="updateApp">Update App State</button>

tests/misc/portal.test.ts

@@ -36,7 +36,7 @@ describe("Portal: Props validation", () => {
   test("target is mandatory", async () => {
     const dev = QWeb.dev;
     QWeb.dev = true;
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -61,7 +61,7 @@ describe("Portal: Props validation", () => {
   test("target is not list", async () => {
     const dev = QWeb.dev;
     QWeb.dev = true;
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -88,7 +88,7 @@ describe("Portal: Basic use and DOM placement", () => {
   test("basic use of portal", async () => {
     const dev = QWeb.dev;
     QWeb.dev = true;
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -113,7 +113,7 @@ describe("Portal: Basic use and DOM placement", () => {
   });
 
   test("conditional use of Portal", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -148,10 +148,10 @@ describe("Portal: Basic use and DOM placement", () => {
   });
 
   test("conditional use of Portal (with sub Component)", async () => {
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<div><t t-esc="props.val"/></div>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -190,7 +190,7 @@ describe("Portal: Basic use and DOM placement", () => {
   });
 
   test("with target in template (before portal)", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -210,7 +210,7 @@ describe("Portal: Basic use and DOM placement", () => {
   });
 
   test("with target in template (after portal)", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -233,7 +233,7 @@ describe("Portal: Basic use and DOM placement", () => {
     const consoleError = console.error;
     console.error = jest.fn(() => {});
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -260,7 +260,7 @@ describe("Portal: Basic use and DOM placement", () => {
 
   test("portal with child and props", async () => {
     const steps: string[] = [];
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span><t t-esc="props.val"/></span>`;
       mounted() {
         steps.push("mounted");
@@ -271,7 +271,7 @@ describe("Portal: Basic use and DOM placement", () => {
         expect(outside.innerHTML).toBe("<span>2</span>");
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -298,7 +298,7 @@ describe("Portal: Basic use and DOM placement", () => {
     const consoleError = console.error;
     console.error = jest.fn(() => {});
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -326,7 +326,7 @@ describe("Portal: Basic use and DOM placement", () => {
     const consoleError = console.error;
     console.error = jest.fn(() => {});
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -354,7 +354,7 @@ describe("Portal: Basic use and DOM placement", () => {
     const consoleError = console.error;
     console.error = jest.fn(() => {});
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -379,7 +379,7 @@ describe("Portal: Basic use and DOM placement", () => {
   });
 
   test("portal with dynamic body", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -405,7 +405,7 @@ describe("Portal: Basic use and DOM placement", () => {
     const consoleError = console.error;
     console.error = jest.fn(() => {});
 
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -439,7 +439,7 @@ describe("Portal: Basic use and DOM placement", () => {
   test("lifecycle hooks of portal sub component are properly called", async () => {
     const steps: any[] = [];
 
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span t-esc="props.val"/>`;
       mounted() {
         steps.push("child:mounted");
@@ -454,7 +454,7 @@ describe("Portal: Basic use and DOM placement", () => {
         steps.push("child:willUnmount");
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -486,7 +486,7 @@ describe("Portal: Basic use and DOM placement", () => {
       "parent:mounted",
       "parent:willPatch",
       "child:mounted",
-      "parent:patched"
+      "parent:patched",
     ]);
 
     parent.state.val = 2;
@@ -499,7 +499,7 @@ describe("Portal: Basic use and DOM placement", () => {
       "parent:willPatch",
       "child:willPatch",
       "child:patched",
-      "parent:patched"
+      "parent:patched",
     ]);
 
     parent.state.hasChild = false;
@@ -515,16 +515,16 @@ describe("Portal: Basic use and DOM placement", () => {
       "parent:patched",
       "parent:willPatch",
       "child:willUnmount",
-      "parent:patched"
+      "parent:patched",
     ]);
   });
 
   test("portal destroys on crash", async () => {
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span t-esc="props.error and this.will.crash" />`;
       state = {};
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -546,11 +546,13 @@ describe("Portal: Basic use and DOM placement", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe("Cannot read property 'crash' of undefined");
+    const regexp =
+      /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
+    expect(error.message).toMatch(regexp);
   });
 
   test("portal manual unmount", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -577,7 +579,7 @@ describe("Portal: Basic use and DOM placement", () => {
 
   test("portal manual unmount with subcomponent", async () => {
     expect.assertions(9);
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`<span>gloria</span>`;
       mounted() {
         expect(outside.contains(this.el)).toBeTruthy();
@@ -586,7 +588,7 @@ describe("Portal: Basic use and DOM placement", () => {
         expect(outside.contains(this.el)).toBeTruthy();
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -614,7 +616,7 @@ describe("Portal: Basic use and DOM placement", () => {
 
 describe("Portal: Events handling", () => {
   test("events triggered on movable pure node are handled", async () => {
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal };
       static template = xml`
         <div>
@@ -638,8 +640,8 @@ describe("Portal: Events handling", () => {
   });
 
   test("events triggered on movable owl components are redirected", async () => {
-    let childInst: Component<any, any> | null = null;
-    class Child extends Component<any, any> {
+    let childInst: Component | null = null;
+    class Child extends Component {
       static template = xml`
          <span t-on-custom="_onCustom" t-esc="props.val"/>`;
 
@@ -652,7 +654,7 @@ describe("Portal: Events handling", () => {
         this.trigger("custom-portal");
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div t-on-custom-portal="_onCustomPortal">
@@ -677,8 +679,8 @@ describe("Portal: Events handling", () => {
 
   test("events triggered on contained movable owl components are redirected", async () => {
     const steps: string[] = [];
-    let childInst: Component<any, any> | null = null;
-    class Child extends Component<any, any> {
+    let childInst: Component | null = null;
+    class Child extends Component {
       static template = xml`
          <span t-on-custom="_onCustom"/>`;
 
@@ -691,7 +693,7 @@ describe("Portal: Events handling", () => {
         this.trigger("custom-portal");
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div t-on-custom="_handled" t-on-custom-portal="_handled">
@@ -717,9 +719,9 @@ describe("Portal: Events handling", () => {
   });
 
   test("Dom events are not mapped", async () => {
-    let childInst: Component<any, any> | null = null;
+    let childInst: Component | null = null;
     const steps: string[] = [];
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`
         <button>child</button>`;
 
@@ -728,7 +730,7 @@ describe("Portal: Events handling", () => {
         childInst = this;
       }
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div t-on-click="_handled">
@@ -741,7 +743,7 @@ describe("Portal: Events handling", () => {
         steps.push(ev.type as string);
       }
     }
-    const bodyListener = ev => {
+    const bodyListener = (ev) => {
       steps.push(`body: ${ev.type}`);
     };
     document.body.addEventListener("click", bodyListener);
@@ -760,22 +762,22 @@ describe("Portal: Events handling", () => {
     fixture.appendChild(outside2);
 
     const steps: Array<string> = [];
-    let childInst: Component<any, any> | null = null;
-    class Child2 extends Component<any, any> {
+    let childInst: Component | null = null;
+    class Child2 extends Component {
       static template = xml`<div>child2</div>`;
       constructor(parent, props) {
         super(parent, props);
         childInst = this;
       }
     }
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static components = { Portal, Child2 };
       static template = xml`
         <Portal target="'#outside2'">
           <Child2 />
         </Portal>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div t-on-custom='_handled'>
@@ -797,11 +799,11 @@ describe("Portal: Events handling", () => {
   });
 
   test("portal's parent's env is not polluted", async () => {
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`
         <button>child</button>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>
@@ -818,22 +820,22 @@ describe("Portal: Events handling", () => {
 
   test("Portal composed with t-slot", async () => {
     const steps: Array<string> = [];
-    let childInst: Component<any, any> | null = null;
-    class Child2 extends Component<any, any> {
+    let childInst: Component | null = null;
+    class Child2 extends Component {
       static template = xml`<div>child2</div>`;
       constructor(parent, props) {
         super(parent, props);
         childInst = this;
       }
     }
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static components = { Portal, Child2 };
       static template = xml`
         <Portal target="'#outside'">
           <t t-slot="default"/>
         </Portal>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Child, Child2 };
       static template = xml`
         <div t-on-custom='_handled'>
@@ -857,11 +859,11 @@ describe("Portal: Events handling", () => {
 
 describe("Portal: UI/UX", () => {
   test("focus is kept across re-renders", async () => {
-    class Child extends Component<any, any> {
+    class Child extends Component {
       static template = xml`
         <input id="target-me" t-att-placeholder="props.val"/>`;
     }
-    class Parent extends Component<any, any> {
+    class Parent extends Component {
       static components = { Portal, Child };
       static template = xml`
         <div>

tests/qweb/__snapshots__/qweb_memory.test.ts.snap

@@ -0,0 +1,37 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`memory t-foreach does not leak stuff in global scope 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('p', p1, c1);
+    let _2 = [3,2,1];
+    if (!_2) { throw new Error('QWeb error: Invalid loop expression')}
+    let _3 = _2;
+    let _4 = _2;
+    if (!(_2 instanceof Array)) {
+        _3 = Object.keys(_2);
+        _4 = Object.values(_2);
+    }
+    let _length3 = _3.length;
+    let _origScope5 = scope;
+    scope = Object.create(scope);
+    for (let i1 = 0; i1 < _length3; i1++) {
+        scope.item_first = i1 === 0
+        scope.item_last = i1 === _length3 - 1
+        scope.item_index = i1
+        scope.item = _3[i1]
+        scope.item_value = _4[i1]
+        let key1 = i1;
+        let _6 = scope['item'];
+        if (_6 != null) {
+            c1.push({text: _6});
+        }
+    }
+    scope = _origScope5;
+    return vn1;
+}"
+`;

tests/qweb/__snapshots__/qweb_t_att.test.ts.snap

@@ -0,0 +1,57 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`qweb t-att t-att-class with multiple classes 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _1 = utils.toClassObj({'a b c':scope['value']});
+    let c2 = [], p2 = {key:2,class:_1};
+    let vn2 = h('div', p2, c2);
+    return vn2;
+}"
+`;
+
+exports[`qweb t-att t-att-class with multiple classes 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _3 = utils.toClassObj({['a b c']:scope['value']});
+    let c4 = [], p4 = {key:4,class:_3};
+    let vn4 = h('div', p4, c4);
+    return vn4;
+}"
+`;
+
+exports[`qweb t-att t-att-class with multiple classes, some of which are duplicate 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _1 = utils.toClassObj({'a b c':scope['value'],'a b d':!scope['value']});
+    let c2 = [], p2 = {key:2,class:_1};
+    let vn2 = h('div', p2, c2);
+    return vn2;
+}"
+`;
+
+exports[`qweb t-att t-att-class with multiple classes, some of which are duplicate 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let _3 = utils.toClassObj({'a b c':scope['value'],'a b d':!scope['value']});
+    let c4 = [], p4 = {key:4,class:_3};
+    let vn4 = h('div', p4, c4);
+    return vn4;
+}"
+`;

tests/qweb/__snapshots__/qweb_t_tag.test.ts.snap

@@ -0,0 +1,71 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`qweb t-tag simple usecases 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let scope = Object.create(context);
+    let result;
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let tag2 = 'div';
+    let vn1 = h(tag2, p1, c1);
+    result = vn1;
+    return result;
+}"
+`;
+
+exports[`qweb t-tag simple usecases 2`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let scope = Object.create(context);
+    let result;
+    let h = this.h;
+    let c3 = [], p3 = {key:3};
+    let tag4 = scope['tag'];
+    let vn3 = h(tag4, p3, c3);
+    result = vn3;
+    c3.push({text: \`text\`});
+    return result;
+}"
+`;
+
+exports[`qweb t-tag with multiple attributes 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let scope = Object.create(context);
+    let result;
+    let h = this.h;
+    let _2 = {'blueberry':true};
+    let _3 = 'raspberry';
+    let c4 = [], p4 = {key:4,attrs:{taste: _3},class:_2};
+    let tag5 = scope['tag'];
+    let vn4 = h(tag5, p4, c4);
+    result = vn4;
+    c4.push({text: \`gooseberry\`});
+    return result;
+}"
+`;
+
+exports[`qweb t-tag with multiple child nodes 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let scope = Object.create(context);
+    let result;
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let tag2 = scope['tag'];
+    let vn1 = h(tag2, p1, c1);
+    result = vn1;
+    c1.push({text: \` pear \`});
+    let c3 = [], p3 = {key:3};
+    let vn3 = h('span', p3, c3);
+    c1.push(vn3);
+    c3.push({text: \`apple\`});
+    c1.push({text: \` strawberry \`});
+    return result;
+}"
+`;

tests/qweb/qweb.test.ts

@@ -1,4 +1,5 @@
 import { QWeb } from "../../src/qweb/index";
+import { config } from "../../src/index";
 import { nextTick, normalize, renderToDOM, renderToString, trim } from "../helpers";
 import { patch } from "../../src/vdom";
 
@@ -13,6 +14,7 @@ let qweb: QWeb;
 
 beforeEach(() => {
   QWeb.TEMPLATES = {};
+  QWeb.nextId = 1;
   qweb = new QWeb();
 });
 
@@ -31,6 +33,21 @@ describe("static templates", () => {
     expect(renderToString(qweb, "test", { text: "hello vdom" })).toBe("hello vdom");
   });
 
+  test("inline template string in t-esc", () => {
+    qweb.addTemplate("test", '<t><t t-esc="`text`"/></t>');
+    expect(renderToString(qweb, "test")).toBe("text");
+  });
+
+  test("inline template string with content in t-esc", () => {
+    qweb.addTemplate("test", '<t><t t-set="v" t-value="1"/><t t-esc="`text${v}`"/></t>');
+    expect(renderToString(qweb, "test")).toBe("text1");
+  });
+
+  test("inline template string with variable in context", () => {
+    qweb.addTemplate("test", '<t><t t-esc="`text ${v}`"/></t>');
+    expect(renderToString(qweb, "test", { v: "from context" })).toBe("text from context");
+  });
+
   test("simple string, with some dynamic value", () => {
     qweb.addTemplate("test", '<t>hello <t t-esc="text"/></t>');
     expect(renderToString(qweb, "test", { text: "vdom" })).toBe("hello vdom");
@@ -51,6 +68,16 @@ describe("static templates", () => {
     expect(renderToString(qweb, "test")).toBe(`<div class="abc">word</div>`);
   });
 
+  test("div with a class attribute with a quote", () => {
+    qweb.addTemplate("test", `<div class="a'bc">word</div>`);
+    expect(renderToString(qweb, "test")).toBe(`<div class="a'bc">word</div>`);
+  });
+
+  test("div with an arbitrary attribute with a quote", () => {
+    qweb.addTemplate("test", `<div abc="a'bc">word</div>`);
+    expect(renderToString(qweb, "test")).toBe(`<div abc="a'bc">word</div>`);
+  });
+
   test("div with a empty class attribute", () => {
     qweb.addTemplate("test", `<div class="">word</div>`);
     expect(renderToString(qweb, "test")).toBe(`<div>word</div>`);
@@ -65,6 +92,19 @@ describe("static templates", () => {
     qweb.addTemplate("test", "<div>hello <!-- comment-->owl</div>");
     expect(renderToString(qweb, "test")).toBe("<div>hello <!-- comment-->owl</div>");
   });
+
+  test("properly handle comments between t-if/t-else", () => {
+    qweb.addTemplate(
+      "test",
+      `
+      <div>
+        <span t-if="true">true</span>
+        <!-- comment-->
+        <span t-else="">owl</span>
+      </div>`
+    );
+    expect(renderToString(qweb, "test")).toBe("<div><span>true</span></div>");
+  });
 });
 
 describe("error handling", () => {
@@ -141,17 +181,56 @@ describe("t-esc", () => {
     qweb.addTemplate("test", `<span t-esc="var">nope</span>`);
     expect(renderToString(qweb, "test")).toBe("<span>nope</span>");
   });
+
   test("t-esc is escaped", () => {
     qweb.addTemplate("test", `<div><t t-set="var"><p>escaped</p></t><t t-esc="var"/></div>`);
     const domRendered = renderToDOM(qweb, "test");
     expect(domRendered.textContent).toBe("<p>escaped</p>");
   });
+
   test("t-esc=0 is escaped", () => {
     qweb.addTemplate("test", `<span><t t-esc="0"/></span>`);
     qweb.addTemplate("testCaller", `<div><t t-call="test"><p>escaped</p></t></div>`);
     const domRendered = renderToDOM(qweb, "testCaller") as HTMLElement;
     expect(domRendered.querySelector("span")!.textContent).toBe("<p>escaped</p>");
   });
+
+  test("div with falsy values", () => {
+    qweb.addTemplate(
+      "test",
+      `
+      <div>
+        <p t-esc="v1"/>
+        <p t-esc="v2"/>
+        <p t-esc="v3"/>
+        <p t-esc="v4"/>
+        <p t-esc="v5"/>
+      </div>`
+    );
+    const vals = {
+      v1: false,
+      v2: undefined,
+      v3: null,
+      v4: 0,
+      v5: "",
+    };
+    expect(renderToString(qweb, "test", vals)).toBe(
+      "<div><p>false</p><p></p><p></p><p>0</p><p></p></div>"
+    );
+  });
+
+  test("t-esc work with spread operator", () => {
+    qweb.addTemplate("test", `<span><t t-esc="[...state.list]"/></span>`);
+    const result = renderToString(qweb, "test", { state: { list: [1, 2] } });
+    expect(result).toBe("<span>1,2</span>");
+  });
+
+  test("t-esc inside t-call, with t-set outside", () => {
+    qweb.addTemplate("main", `<div><t t-set="v">Hi</t><t t-call="sub"/></div>`);
+    qweb.addTemplate("sub", `<span t-esc="v"/>`);
+    const result = renderToString(qweb, "main");
+    expect(result).toBe("<div><span>Hi</span></div>");
+  });
 });
 
 describe("t-raw", () => {
@@ -176,6 +255,13 @@ describe("t-raw", () => {
       "<span><span>hello</span><ok>world</ok></span>"
     );
   });
+
+  test("t-raw with comment", () => {
+    qweb.addTemplate("test", `<span><t t-raw="var"/></span>`);
+    expect(renderToString(qweb, "test", { var: "<p>text<!-- top secret --></p>" })).toBe(
+      "<span><p>text<!-- top secret --></p></span>"
+    );
+  });
 });
 
 describe("t-set", () => {
@@ -258,6 +344,18 @@ describe("t-set", () => {
     );
   });
 
+  test("t-set with content and sub t-esc", () => {
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <t t-set="setvar"><t t-esc="beep"/> boop</t>
+        <t t-esc="setvar"/>
+      </div>`
+    );
+
+    expect(renderToString(qweb, "test", { beep: "beep" })).toBe("<div>beep boop</div>");
+  });
+
   test("evaluate value expression, part 2", () => {
     qweb.addTemplate(
       "test",
@@ -419,7 +517,7 @@ describe("t-if", () => {
       cond3: false,
       cond4: false,
       m: 5,
-      n: 2
+      n: 2,
     };
     expect(normalize(renderToString(qweb, "test", context))).toBe("<div>andormgtnlt</div>");
   });
@@ -558,7 +656,7 @@ describe("attributes", () => {
   test("object", () => {
     qweb.addTemplate("test", `<div t-att="value"/>`);
     const result = renderToString(qweb, "test", {
-      value: { a: 1, b: 2, c: 3 }
+      value: { a: 1, b: 2, c: 3 },
     });
     expect(result).toBe(`<div a="1" b="2" c="3"></div>`);
   });
@@ -617,7 +715,7 @@ describe("attributes", () => {
     const result = renderToString(qweb, "test", {
       value1: 0,
       value2: 1,
-      value3: 2
+      value3: 2,
     });
     expect(result).toBe(`<div foo="a 0 is 1 of 2 ]"></div>`);
   });
@@ -636,7 +734,7 @@ describe("attributes", () => {
     const result = renderToString(qweb, "test", {
       bar: 0,
       baz: 1,
-      qux: { qux: "<>" }
+      qux: { qux: "<>" },
     });
     const expected = '<div foo="<foo" bar="0" baz="<1>" qux="<>"></div>';
     expect(result).toBe(expected);
@@ -648,6 +746,12 @@ describe("attributes", () => {
     expect(result).toBe(`<div class="hello world"></div>`);
   });
 
+  test("class and t-att-class should combine together", () => {
+    qweb.addTemplate("test", `<div t-att-class="value" class="hello" />`);
+    const result = renderToString(qweb, "test", { value: "world" });
+    expect(result).toBe(`<div class="world hello"></div>`);
+  });
+
   test("class and t-attf-class with ternary operation", () => {
     qweb.addTemplate("test", `<div class="hello" t-attf-class="{{value ? 'world' : ''}}"/>`);
     const result = renderToString(qweb, "test", { value: true });
@@ -667,7 +771,7 @@ describe("t-call (template calling", () => {
     qweb.addTemplate("caller", '<div><t t-call="_basic-callee"/></div>');
     const expected = "<div><span>ok</span></div>";
     expect(renderToString(qweb, "caller")).toBe(expected);
-    expect(qweb.subTemplates["_basic-callee"].toString()).toMatchSnapshot();
+    expect(qweb.subTemplates["_basic-callee"]).toBeTruthy();
   });
 
   test("basic caller, no parent node", () => {
@@ -675,7 +779,7 @@ describe("t-call (template calling", () => {
     qweb.addTemplate("caller", '<t t-call="_basic-callee"/>');
     const expected = "<div>ok</div>";
     expect(renderToString(qweb, "caller")).toBe(expected);
-    expect(qweb.subTemplates["_basic-callee"].toString()).toMatchSnapshot();
+    expect(qweb.subTemplates["_basic-callee"]).toBeTruthy();
   });
 
   test("t-call with t-if", () => {
@@ -683,13 +787,14 @@ describe("t-call (template calling", () => {
     qweb.addTemplate("caller", '<div><t t-if="flag" t-call="sub"/></div>');
     const expected = "<div><span>ok</span></div>";
     expect(renderToString(qweb, "caller", { flag: true })).toBe(expected);
-    expect(qweb.subTemplates["sub"].toString()).toMatchSnapshot();
+    expect(qweb.subTemplates["sub"]).toBeTruthy();
   });
 
-  test("t-call not allowed on a non t node", () => {
-    qweb.addTemplate("_basic-callee", "<t>ok</t>");
+  test("t-call allowed on a non t node", () => {
+    qweb.addTemplate("_basic-callee", "<span>ok</span>");
     qweb.addTemplate("caller", '<div t-call="_basic-callee"/>');
-    expect(() => renderToString(qweb, "caller")).toThrow("Invalid tag");
+    const expected = "<div><span>ok</span></div>";
+    expect(renderToString(qweb, "caller")).toBe(expected);
   });
 
   test("with unused body", () => {
@@ -818,7 +923,8 @@ describe("t-call (template calling", () => {
     `);
     const expected = "<div><span>hey</span></div>";
     expect(renderToString(qweb, "recursive")).toBe(expected);
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const subId = qweb.subTemplates["recursive"];
+    const recursiveFn = QWeb.subTemplates[subId] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -846,7 +952,8 @@ describe("t-call (template calling", () => {
     expect(renderToString(qweb, "Parent", { root }, { fiber: { vars: {}, scope: {} } })).toBe(
       expected
     );
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const subId = qweb.subTemplates["nodeTemplate"];
+    const recursiveFn = QWeb.subTemplates[subId] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -873,7 +980,41 @@ describe("t-call (template calling", () => {
     const expected =
       "<div><div><p>a</p><div><p>b</p><div><p>d</p></div></div><div><p>c</p></div></div></div>";
     expect(renderToString(qweb, "Parent", { root }, { fiber: {} })).toBe(expected);
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const subId = qweb.subTemplates["nodeTemplate"];
+    const recursiveFn = QWeb.subTemplates[subId] as any;
+    expect(recursiveFn.toString()).toMatchSnapshot();
+  });
+
+  test("recursive template, part 4: with t-set recursive index", () => {
+    qweb.addTemplates(`
+        <templates>
+            <div t-name="Parent">
+                <t t-call="nodeTemplate">
+                    <t t-set="recursive_idx" t-value="1"/>
+                    <t t-set="node" t-value="root"/>
+                </t>
+            </div>
+            <div t-name="nodeTemplate">
+                <t t-set="recursive_idx" t-value="recursive_idx + 1"/>
+                <p><t t-esc="node.val"/> <t t-esc="recursive_idx"/></p>
+                <t t-foreach="node.children or []" t-as="subtree">
+                    <t t-call="nodeTemplate">
+                        <t t-set="node" t-value="subtree"/>
+                    </t>
+                </t>
+            </div>
+
+        </templates>
+    `);
+    const root = {
+      val: "a",
+      children: [{ val: "b", children: [{ val: "c", children: [{ val: "d" }] }] }],
+    };
+    const expected =
+      "<div><div><p>a 2</p><div><p>b 3</p><div><p>c 4</p><div><p>d 5</p></div></div></div></div></div>";
+    expect(renderToString(qweb, "Parent", { root })).toBe(expected);
+    const subId = qweb.subTemplates["nodeTemplate"];
+    const recursiveFn = QWeb.subTemplates[subId] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -945,6 +1086,52 @@ describe("t-call (template calling", () => {
     const context = { list: [{ val: 1 }, { val: 2 }, { val: 3 }] };
     expect(trim(renderToString(qweb, "wrapper", context))).toBe(expected);
   });
+
+  test("two different QWeb instances, and shared templates", () => {
+    QWeb.registerTemplate("sub", `<span>ok</span>`);
+    QWeb.registerTemplate("main", `<div><t t-call="sub"/></div>`);
+
+    const qweb1 = new QWeb();
+    const qweb2 = new QWeb();
+
+    expect(renderToString(qweb1, "main")).toBe("<div><span>ok</span></div>");
+    expect(renderToString(qweb2, "main")).toBe("<div><span>ok</span></div>");
+  });
+
+  test("t-call with t-set inside and body text content", () => {
+    qweb.addTemplate("sub", `<p><t t-esc="val"/></p>`);
+    qweb.addTemplate(
+      "main",
+      `
+      <div>
+        <t t-call="sub">
+          <t t-set="val">yip yip</t>
+        </t>
+      </div>`
+    );
+    const expected = "<div><p>yip yip</p></div>";
+    expect(renderToString(qweb, "main")).toBe(expected);
+  });
+
+  test("t-call with body content as root of a template", () => {
+    qweb.addTemplate("antony", `<foo><t t-raw="0"/></foo>`);
+    qweb.addTemplate("main", `<t><t t-call="antony"><p>antony</p></t></t>`);
+    const expected = "<foo><p>antony</p></foo>";
+    expect(renderToString(qweb, "main")).toBe(expected);
+  });
+
+  test("dynamic t-call", () => {
+    qweb.addTemplate("foo", `<foo><t t-esc="val"/></foo>`);
+    qweb.addTemplate("bar", `<bar><t t-esc="val"/></bar>`);
+    qweb.addTemplate("main", `<div><t t-call="{{template}}"/></div>`);
+    const expected = "<div><foo>foo</foo></div>";
+    expect(renderToString(qweb, "main", { template: "foo", val: "foo" })).toBe(expected);
+    const expected2 = "<div><bar>quux</bar></div>";
+    expect(renderToString(qweb, "main", { template: "bar", val: "quux" })).toBe(expected2);
+    // duplicate call because there was a specific bug with some id that was
+    // incremented each rendering.
+    expect(renderToString(qweb, "main", { template: "bar", val: "quux" })).toBe(expected2);
+  });
 });
 
 describe("foreach", () => {
@@ -1035,6 +1222,63 @@ describe("foreach", () => {
     );
   });
 
+  test("t-call without body in t-foreach in t-foreach", () => {
+    qweb.addTemplate(
+      "test_called",
+      `<t>
+        <t t-set="c" t-value="'x' + '_' + a + '_'+ b" />
+        [<t t-esc="a" />]
+        [<t t-esc="b" />]
+        [<t t-esc="c" />]
+       </t>`
+    );
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <t t-foreach="numbers" t-as="a">
+          <t t-foreach="letters" t-as="b">
+            <t t-call="test_called" />
+          </t>
+          <span t-esc="c"/>
+        </t>
+        <span>[<t t-esc="a" />][<t t-esc="b" />][<t t-esc="c" />]</span>
+      </div>`
+    );
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    expect(renderToString(qweb, "test", context)).toBe(
+      "<div> [1] [a] [x_1_a]  [1] [b] [x_1_b] <span></span> [2] [a] [x_2_a]  [2] [b] [x_2_b] <span></span> [3] [a] [x_3_a]  [3] [b] [x_3_b] <span></span><span>[][][]</span></div>"
+    );
+  });
+
+  test("t-call with body in t-foreach in t-foreach", () => {
+    qweb.addTemplate(
+      "test_called",
+      `<t>
+        [<t t-esc="a" />]
+        [<t t-esc="b" />]
+        [<t t-esc="c" />]
+       </t>`
+    );
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <t t-foreach="numbers" t-as="a">
+          <t t-foreach="letters" t-as="b">
+            <t t-call="test_called" >
+              <t t-set="c" t-value="'x' + '_' + a + '_'+ b" />
+            </t>
+          </t>
+          <span t-esc="c"/>
+        </t>
+        <span>[<t t-esc="a" />][<t t-esc="b" />][<t t-esc="c" />]</span>
+      </div>`
+    );
+    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
+    expect(renderToString(qweb, "test", context)).toBe(
+      "<div> [1] [a] [x_1_a]  [1] [b] [x_1_b] <span></span> [2] [a] [x_2_a]  [2] [b] [x_2_b] <span></span> [3] [a] [x_3_a]  [3] [b] [x_3_b] <span></span><span>[][][]</span></div>"
+    );
+  });
+
   test("throws error if invalid loop expression", () => {
     qweb.addTemplate(
       "test",
@@ -1130,7 +1374,7 @@ describe("t-on", () => {
       {
         add() {
           a = 3;
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1153,7 +1397,7 @@ describe("t-on", () => {
         },
         handleDblClick() {
           steps.push("dblclick");
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1173,7 +1417,7 @@ describe("t-on", () => {
       {
         add(n) {
           a = a + n;
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1190,7 +1434,7 @@ describe("t-on", () => {
       {
         add({ val }) {
           a = a + val;
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1207,7 +1451,7 @@ describe("t-on", () => {
       {
         doSomething(arg) {
           expect(arg).toEqual({});
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1223,7 +1467,7 @@ describe("t-on", () => {
       {
         doSomething(arg) {
           expect(arg).toEqual({});
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1245,7 +1489,7 @@ describe("t-on", () => {
       {
         activate(action) {
           expect(action).toBe("someval");
-        }
+        },
       },
       { handlers: [] }
     );
@@ -1258,7 +1502,7 @@ describe("t-on", () => {
     let owner = {
       add() {
         expect(this).toBe(owner);
-      }
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
     (<HTMLElement>node).click();
@@ -1268,8 +1512,8 @@ describe("t-on", () => {
     qweb.addTemplate("test", `<button t-on-click="state.counter++">Click</button>`);
     let owner = {
       state: {
-        counter: 0
-      }
+        counter: 0,
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
     expect(owner.state.counter).toBe(0);
@@ -1282,10 +1526,10 @@ describe("t-on", () => {
     let owner = {
       state: {
         counter: 0,
-        incrementCounter: inc => {
+        incrementCounter: (inc) => {
           owner.state.counter += inc;
-        }
-      }
+        },
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
     expect(owner.state.counter).toBe(0);
@@ -1297,8 +1541,8 @@ describe("t-on", () => {
     qweb.addTemplate("test", `<button t-on-click="state.flag = !state.flag">Toggle</button>`);
     let owner = {
       state: {
-        flag: true
-      }
+        flag: true,
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
     expect(owner.state.flag).toBe(true);
@@ -1315,8 +1559,8 @@ describe("t-on", () => {
         return n + 1;
       },
       state: {
-        n: 11
-      }
+        n: 11,
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
     expect(owner.state.n).toBe(11);
@@ -1332,7 +1576,7 @@ describe("t-on", () => {
     let owner = {
       update() {
         expect(this).toBe(owner);
-      }
+      },
     };
 
     const node = renderToDOM(qweb, "main", owner, { handlers: [] });
@@ -1349,7 +1593,7 @@ describe("t-on", () => {
         expect(this).toBe(owner);
         expect(val).toBe(444);
       },
-      value: 444
+      value: 444,
     };
 
     const node = renderToDOM(qweb, "main", owner, { handlers: [] });
@@ -1378,7 +1622,7 @@ describe("t-on", () => {
       onClickPreventedAndStopped(e) {
         expect(e.defaultPrevented).toBe(true);
         expect(e.cancelBubble).toBe(true);
-      }
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
 
@@ -1404,7 +1648,7 @@ describe("t-on", () => {
       },
       onClickSelf(e) {
         steps.push("onClickSelf");
-      }
+      },
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
 
@@ -1428,10 +1672,10 @@ describe("t-on", () => {
     );
     let steps: boolean[] = [];
     let owner = {
-      onClick() {}
+      onClick() {},
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
-    (<HTMLElement>node).addEventListener("click", function(e) {
+    (<HTMLElement>node).addEventListener("click", function (e) {
       steps.push(e.defaultPrevented);
     });
 
@@ -1453,10 +1697,10 @@ describe("t-on", () => {
     );
     let steps: boolean[] = [];
     let owner = {
-      onClick() {}
+      onClick() {},
     };
     const node = renderToDOM(qweb, "test", owner, { handlers: [] });
-    (<HTMLElement>node).addEventListener("click", function(e) {
+    (<HTMLElement>node).addEventListener("click", function (e) {
       steps.push(e.defaultPrevented);
     });
 
@@ -1484,13 +1728,13 @@ describe("t-on", () => {
     const owner = {
       projects: [
         { id: 1, name: "Project 1" },
-        { id: 2, name: "Project 2" }
+        { id: 2, name: "Project 2" },
       ],
 
       onEdit(projectId, ev) {
         expect(ev.defaultPrevented).toBe(true);
         steps.push(projectId);
-      }
+      },
     };
 
     const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
@@ -1515,7 +1759,7 @@ describe("t-on", () => {
     );
     const node = renderToDOM(qweb, "test", {}, { handlers: [] });
 
-    node.addEventListener("click", e => {
+    node.addEventListener("click", (e) => {
       expect(e.defaultPrevented).toBe(true);
     });
 
@@ -1531,7 +1775,7 @@ describe("t-on", () => {
       text: "Click here",
       onClick() {
         steps.push("onClick");
-      }
+      },
     };
 
     const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
@@ -1550,7 +1794,7 @@ describe("t-on", () => {
       html: "Click <b>here</b>",
       onClick() {
         steps.push("onClick");
-      }
+      },
     };
 
     const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
@@ -1560,6 +1804,31 @@ describe("t-on", () => {
 
     expect(steps).toEqual(["onClick"]);
   });
+
+  test("t-on with .capture modifier", () => {
+    expect.assertions(2);
+    qweb.addTemplate(
+      "test",
+      `<div t-on-click.capture="onCapture">
+        <button t-on-click="doSomething">Button</button>
+      </div>`
+    );
+
+    const steps: string[] = [];
+    const owner = {
+      onCapture() {
+        steps.push("captured");
+      },
+      doSomething() {
+        steps.push("normal");
+      },
+    };
+    const node = renderToDOM(qweb, "test", owner, { handlers: [] });
+
+    const button = (<HTMLElement>node).getElementsByTagName("button")[0];
+    button.click();
+    expect(steps).toEqual(["captured", "normal"]);
+  });
 });
 
 describe("t-ref", () => {
@@ -1595,8 +1864,7 @@ describe("t-ref", () => {
 
 describe("loading templates", () => {
   test("can initialize qweb with a string", () => {
-    const templates = `
-      <?xml version="1.0" encoding="UTF-8"?>
+    const templates = `<?xml version="1.0" encoding="UTF-8"?>
       <templates id="template" xml:space="preserve">
         <div t-name="hey">jupiler</div>
       </templates>`;
@@ -1605,8 +1873,7 @@ describe("loading templates", () => {
   });
 
   test("can load a few templates from a xml string", () => {
-    const data = `
-      <?xml version="1.0" encoding="UTF-8"?>
+    const data = `<?xml version="1.0" encoding="UTF-8"?>
       <templates id="template" xml:space="preserve">
 
         <t t-name="items"><li>ok</li><li>foo</li></t>
@@ -1625,7 +1892,7 @@ describe("loading templates", () => {
   });
 });
 
-describe("special cases for some boolean html attributes/properties", () => {
+describe("special cases for some specific html attributes/properties", () => {
   test("input type= checkbox, with t-att-checked", () => {
     qweb.addTemplate("test", `<input type="checkbox" t-att-checked="flag"/>`);
     const result = renderToString(qweb, "test", { flag: true });
@@ -1652,6 +1919,76 @@ describe("special cases for some boolean html attributes/properties", () => {
     );
     renderToString(qweb, "test", { flag: true });
   });
+
+  test("input with t-att-value", () => {
+    // render input with initial value
+    qweb.addTemplate("test", `<input  t-att-value="v"/>`);
+    const vnode1 = qweb.render("test", { v: "zucchini" });
+    const vnode2 = patch(document.createElement("input"), vnode1);
+    let elm = vnode2.elm as HTMLInputElement;
+    expect(elm.value).toBe("zucchini");
+
+    // change value manually in input, to simulate user input
+    elm.value = "tomato";
+    expect(elm.value).toBe("tomato");
+
+    // rerender with a different value, and patch actual dom, to check that
+    // input value was properly reset by owl
+    const vnode3 = qweb.render("test", { v: "potato" });
+    patch(vnode2, vnode3);
+    expect(elm.value).toBe("potato");
+  });
+
+  test("input of type checkbox with t-att-indeterminate", () => {
+    qweb.addTemplate("test", `<input type="checkbox" t-att-indeterminate="v"/>`);
+    const vnode1 = qweb.render("test", { v: true });
+    const vnode2 = patch(document.createElement("input"), vnode1);
+    let elm = vnode2.elm as HTMLInputElement;
+    expect(elm.indeterminate).toBe(true);
+  });
+
+  test("textarea with t-att-value", () => {
+    // render input with initial value
+    qweb.addTemplate("test", `<textarea  t-att-value="v"/>`);
+    const vnode1 = qweb.render("test", { v: "zucchini" });
+    const vnode2 = patch(document.createElement("textarea"), vnode1);
+    let elm = vnode2.elm as HTMLInputElement;
+    expect(elm.value).toBe("zucchini");
+
+    // change value manually in textarea, to simulate user textarea
+    elm.value = "tomato";
+    expect(elm.value).toBe("tomato");
+
+    // rerender with a different value, and patch actual dom, to check that
+    // textarea value was properly reset by owl
+    const vnode3 = qweb.render("test", { v: "potato" });
+    patch(vnode2, vnode3);
+    expect(elm.value).toBe("potato");
+  });
+
+  test("select with t-att-value", () => {
+    const template = `
+      <select t-att-value="value">
+        <option value="potato">Potato</option>
+        <option value="tomato">Tomato</option>
+        <option value="onion">Onion</option>
+      </select>`;
+    qweb.addTemplate("test", template);
+    const vnode1 = qweb.render("test", { value: "tomato" });
+    const vnode2 = patch(document.createElement("select"), vnode1);
+    let elm = vnode2.elm as HTMLSelectElement;
+    expect(elm.value).toBe("tomato");
+
+    elm.value = "potato";
+    expect(elm.value).toBe("potato");
+
+    // rerender with a different value, and patch actual dom, to check that
+    // select value was properly reset by owl
+    const vnode3 = qweb.render("test", { value: "onion" });
+    patch(vnode2, vnode3);
+    expect(elm.value).toBe("onion");
+    expect(qweb.templates.test.fn.toString()).toMatchSnapshot();
+  });
 });
 
 describe("whitespace handling", () => {
@@ -1716,7 +2053,7 @@ describe("t-key", () => {
     );
     expect(
       renderToString(qweb, "test", {
-        beers: [{ id: 12, name: "Chimay Rouge" }]
+        beers: [{ id: 12, name: "Chimay Rouge" }],
       })
     ).toMatchSnapshot();
   });
@@ -1829,9 +2166,9 @@ describe("properly support svg", () => {
 describe("translation support", () => {
   test("can translate node content", () => {
     const translations = {
-      word: "mot"
+      word: "mot",
     };
-    const translateFn = expr => translations[expr] || expr;
+    const translateFn = (expr) => translations[expr] || expr;
     const qweb = new QWeb({ translateFn });
     qweb.addTemplate("test", "<div>word</div>");
     expect(renderToString(qweb, "test")).toBe("<div>mot</div>");
@@ -1839,9 +2176,9 @@ describe("translation support", () => {
 
   test("does not translate node content if disabled", () => {
     const translations = {
-      word: "mot"
+      word: "mot",
     };
-    const translateFn = expr => translations[expr] || expr;
+    const translateFn = (expr) => translations[expr] || expr;
     const qweb = new QWeb({ translateFn });
     qweb.addTemplate(
       "test",
@@ -1856,9 +2193,9 @@ describe("translation support", () => {
 
   test("some attributes are translated", () => {
     const translations = {
-      word: "mot"
+      word: "mot",
     };
-    const translateFn = expr => translations[expr] || expr;
+    const translateFn = (expr) => translations[expr] || expr;
     const qweb = new QWeb({ translateFn });
     qweb.addTemplate(
       "test",
@@ -1875,6 +2212,28 @@ describe("translation support", () => {
       '<div><p label="mot">mot</p><p title="mot">mot</p><p placeholder="mot">mot</p><p alt="mot">mot</p><p something="word">mot</p></div>'
     );
   });
+
+  test("can add additional attributes to the list of translatable attributes", () => {
+    const translations = {
+      word: "mot",
+    };
+    const translateFn = (expr) => translations[expr] || expr;
+    const qweb = new QWeb({ translateFn });
+    config.translatableAttributes.push("potato");
+    qweb.addTemplate("test", `<div tomato="word" potato="word">text</div>`);
+    expect(renderToString(qweb, "test")).toBe('<div tomato="word" potato="mot">text</div>');
+  });
+
+  test("translation is done on the trimmed text, with extra spaces readded after", () => {
+    const translations = {
+      word: "mot",
+    };
+    const translateFn = jest.fn((expr) => translations[expr] || expr);
+    const qweb = new QWeb({ translateFn });
+    qweb.addTemplate("test", "<div> word </div>");
+    expect(renderToString(qweb, "test")).toBe("<div> mot </div>");
+    expect(translateFn).toHaveBeenCalledWith("word");
+  });
 });
 
 describe("t-key tests", () => {

tests/qweb/qweb_expressions.test.ts

@@ -6,12 +6,12 @@ describe("tokenizer", () => {
 
     expect(tokenize("{}")).toEqual([
       { type: "LEFT_BRACE", value: "{" },
-      { type: "RIGHT_BRACE", value: "}" }
+      { type: "RIGHT_BRACE", value: "}" },
     ]);
     expect(tokenize("{ }}")).toEqual([
       { type: "LEFT_BRACE", value: "{" },
       { type: "RIGHT_BRACE", value: "}" },
-      { type: "RIGHT_BRACE", value: "}" }
+      { type: "RIGHT_BRACE", value: "}" },
     ]);
     expect(tokenize("a")).toEqual([{ type: "SYMBOL", value: "a" }]);
     expect(tokenize("true")).toEqual([{ type: "SYMBOL", value: "true" }]);
@@ -25,15 +25,15 @@ describe("tokenizer", () => {
       { type: "SYMBOL", value: "a" },
       { type: "COLON", value: ":" },
       { type: "VALUE", value: "2" },
-      { type: "RIGHT_BRACE", value: "}" }
+      { type: "RIGHT_BRACE", value: "}" },
     ]);
     expect(tokenize("a,")).toEqual([
       { type: "SYMBOL", value: "a" },
-      { type: "COMMA", value: "," }
+      { type: "COMMA", value: "," },
     ]);
     expect(tokenize("][")).toEqual([
       { type: "RIGHT_BRACKET", value: "]" },
-      { type: "LEFT_BRACKET", value: "[" }
+      { type: "LEFT_BRACKET", value: "[" },
     ]);
   });
 
@@ -44,11 +44,23 @@ describe("tokenizer", () => {
       { type: "OPERATOR", value: "<" },
       { type: "OPERATOR", value: ">" },
       { type: "OPERATOR", value: "!==" },
-      { type: "OPERATOR", value: "!=" }
+      { type: "OPERATOR", value: "!=" },
     ]);
     expect(tokenize("typeof a")).toEqual([
       { type: "OPERATOR", value: "typeof " },
-      { type: "SYMBOL", value: "a" }
+      { type: "SYMBOL", value: "a" },
+    ]);
+
+    expect(tokenize("a...1")).toEqual([
+      { type: "SYMBOL", value: "a" },
+      { type: "OPERATOR", value: "..." },
+      { type: "VALUE", value: "1" },
+    ]);
+
+    expect(tokenize("a in b")).toEqual([
+      { type: "SYMBOL", value: "a" },
+      { type: "OPERATOR", value: "in " },
+      { type: "SYMBOL", value: "b" },
     ]);
   });
 
@@ -64,7 +76,7 @@ describe("tokenizer", () => {
     expect(tokenize('"hello ged"')).toEqual([{ type: "VALUE", value: '"hello ged"' }]);
     expect(tokenize('"hello ged"}')).toEqual([
       { type: "VALUE", value: '"hello ged"' },
-      { type: "RIGHT_BRACE", value: "}" }
+      { type: "RIGHT_BRACE", value: "}" },
     ]);
     expect(tokenize('"hello \\"ged\\""')).toEqual([{ type: "VALUE", value: '"hello \\"ged\\""' }]);
   });
@@ -128,6 +140,7 @@ describe("expression evaluation", () => {
     expect(compileExpr("color === 'black'", {})).toBe("scope['color']==='black'");
     expect(compileExpr("'li_'+item", {})).toBe("'li_'+scope['item']");
     expect(compileExpr("state.val > 1", {})).toBe("scope['state'].val>1");
+    expect(compileExpr("a in b", {})).toBe("scope['a']in scope['b']");
   });
 
   test("boolean operations", () => {
@@ -177,4 +190,37 @@ describe("expression evaluation", () => {
     expect(compileExpr("a -= b", {})).toBe("scope['a']-=scope['b']");
     expect(compileExpr("a.b = !a.b", {})).toBe("scope['a'].b=!scope['a'].b");
   });
+
+  test("spread operator", () => {
+    expect(compileExpr("[...state.list]", {})).toBe("[...scope['state'].list]");
+    expect(compileExpr("f(...state.list)", {})).toBe("scope['f'](...scope['state'].list)");
+    expect(compileExpr("f([...list])", {})).toBe("scope['f']([...scope['list']])");
+  });
+
+  test("works with builtin properties", () => {
+    expect(compileExpr("state.constructor.name", {})).toBe("scope['state'].constructor.name");
+  });
+
+  test("works with shortcut object key description", () => {
+    expect(compileExpr("{a}", {})).toBe("{a:scope['a']}");
+    expect(compileExpr("{a,b}", {})).toBe("{a:scope['a'],b:scope['b']}");
+    expect(compileExpr("{a,b:3,c}", {})).toBe("{a:scope['a'],b:3,c:scope['c']}");
+  });
+
+  test("works with short object description and lists ", () => {
+    expect(compileExpr("[a, b]", {})).toBe("[scope['a'],scope['b']]");
+    expect(compileExpr("[a, b, c]", {})).toBe("[scope['a'],scope['b'],scope['c']]");
+    expect(compileExpr("[a, {b, c},d]", {})).toBe(
+      "[scope['a'],{b:scope['b'],c:scope['c']},scope['d']]"
+    );
+    expect(compileExpr("{a:[b, {c, d: e}]}", {})).toBe(
+      "{a:[scope['b'],{c:scope['c'],d:scope['e']}]}"
+    );
+  });
+
+  test("template strings", () => {
+    expect(compileExpr("`hey`", {})).toBe("`hey`");
+    expect(compileExpr("`hey ${you}`", {})).toBe("`hey ${scope['you']}`");
+    expect(compileExpr("`hey ${1 + 2}`", {})).toBe("`hey ${1+2}`");
+  });
 });

tests/qweb/qweb_memory.test.ts

@@ -0,0 +1,14 @@
+import { QWeb } from "../../src/qweb/index";
+import { renderToString } from "../helpers";
+
+describe("memory", () => {
+  test("t-foreach does not leak stuff in global scope", () => {
+    let qweb = new QWeb();
+    const initialNumberOfGlobals = Object.keys(window).length;
+    qweb.addTemplate("test", `<p><t t-foreach="[3, 2, 1]" t-as="item"><t t-esc="item"/></t></p>`);
+    const result = renderToString(qweb, "test");
+    const expected = `<p>321</p>`;
+    expect(result).toBe(expected);
+    expect(Object.keys(window).length).toBe(initialNumberOfGlobals);
+  });
+});

tests/qweb/qweb_t_att.test.ts

@@ -0,0 +1,36 @@
+import { QWeb } from "../../src/qweb/index";
+import { renderToString } from "../helpers";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+function render(template, context = {}) {
+  const qweb = new QWeb();
+  qweb.addTemplate("test", template);
+  return renderToString(qweb, "test", context);
+}
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+describe("qweb t-att", () => {
+  test("t-att-class with multiple classes", () => {
+    expect(render(`<div t-att-class="{'a b c': value}" />`, { value: true })).toBe(
+      '<div class="a b c"></div>'
+    );
+    expect(render(`<div t-att-class="{['a b c']: value}" />`, { value: true })).toBe(
+      '<div class="a b c"></div>'
+    );
+  });
+
+  test("t-att-class with multiple classes, some of which are duplicate", () => {
+    expect(render(`<div t-att-class="{'a b c': value, 'a b d': !value}" />`, { value: true })).toBe(
+      '<div class="a b c"></div>'
+    );
+    expect(
+      render(`<div t-att-class="{'a b c': value, 'a b d': !value}" />`, { value: false })
+    ).toBe('<div class="a b d"></div>');
+  });
+});

tests/qweb/qweb_t_tag.test.ts

@@ -0,0 +1,42 @@
+import { QWeb } from "../../src/qweb/index";
+import { renderToString } from "../helpers";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+function render(template, context = {}) {
+  const qweb = new QWeb();
+  qweb.addTemplate("test", template);
+  return renderToString(qweb, "test", context);
+}
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+describe("qweb t-tag", () => {
+  test("simple usecases", () => {
+    expect(render(`<t t-tag="'div'"></t>`)).toBe("<div></div>");
+    expect(render(`<t t-tag="tag">text</t>`, { tag: "span" })).toBe("<span>text</span>");
+  });
+
+  test("with multiple child nodes", () => {
+    const template = `
+            <t t-tag="tag">
+                pear
+                <span>apple</span>
+                strawberry
+            </t>`;
+    expect(render(template, { tag: "div" })).toBe(
+      "<div> pear <span>apple</span> strawberry </div>"
+    );
+  });
+
+  test("with multiple attributes", () => {
+    const template = `
+            <t t-tag="tag" class="blueberry" taste="raspberry">gooseberry</t>`;
+    const expected = `<div taste=\"raspberry\" class=\"blueberry\">gooseberry</div>`;
+    expect(render(template, { tag: "div" })).toBe(expected);
+  });
+});