[REL] v1.0.0-beta1

closes #525
closes #526

README.md

@@ -104,8 +104,8 @@ Submit a PR!
 
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-1.0.0-alpha5.js](https://github.com/odoo/owl/releases/download/v1.0.0-alpha5/owl.js)
+- [owl-1.0.0-beta1.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta1/owl.js)
-- [owl-1.0.0-alpha5.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-alpha5/owl.min.js)
+- [owl-1.0.0-beta1.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta1/owl.min.js)
 
 Some npm scripts are available:
 

doc/learning/testing_components.md

@@ -1,10 +1,9 @@
-# 🦉 Testing and Debugging Owl components 🦉
+# 🦉 Testing Owl components 🦉
 
 ## Content
 
 - [Overview](#overview)
 - [Unit Tests](#unit-tests)
-- [Debugging](#debugging)
 
 ## Overview
 
@@ -131,81 +130,3 @@ function afterUpdates() {
   });
 }
 ```
-
-## 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,
-the following code can simply be copy/pasted in an application. Once it is
-executed, it will log a lot of information on each component main hooks.
-
-```js
-let current;
-Object.defineProperty(owl.Component, "current", {
-  get() {
-    return current;
-  },
-  set(comp) {
-    current = comp;
-    const name = comp.constructor.name;
-    let __owl__;
-    Object.defineProperty(current, "__owl__", {
-      get() {
-        return __owl__;
-      },
-      set(val) {
-        __owl__ = val;
-        debugComponent(comp, name, __owl__.id);
-      }
-    });
-  }
-});
-
-function toStr(props) {
-  let str = JSON.stringify(props || {});
-  if (str.length > 200) {
-    str = str.slice(0, 200) + "...";
-  }
-  return str;
-}
-
-function debugComponent(component, name, id) {
-  console.log(`[DEBUG] constructor ${name}<id=${id}>, props=${toStr(component.props)}`);
-  owl.hooks.onWillStart(() => {
-    console.log(`[DEBUG] willStart: '${name}<id=${id}>'`);
-  });
-  owl.hooks.onMounted(() => {
-    console.log(`[DEBUG] mounted: '${name}<id=${id}>'`);
-  });
-  owl.hooks.onWillUpdateProps(nextProps => {
-    console.log(`[DEBUG] willUpdateProps: '${name}<id=${id}> nextprops=${toStr(nextProps)}`);
-  });
-  owl.hooks.onWillPatch(() => {
-    console.log(`[DEBUG] willPatch: '${name}<id=${id}>'`);
-  });
-  owl.hooks.onPatched(() => {
-    console.log(`[DEBUG] patched: '${name}<id=${id}>'`);
-  });
-  owl.hooks.onWillUnmount(() => {
-    console.log(`[DEBUG] willUnmount: '${name}<id=${id}>'`);
-  });
-  const __render = component.__render.bind(component);
-  component.__render = function(...args) {
-    console.log(`[DEBUG] rendering template: '${name}<id=${id}>'`);
-    __render(...args);
-  };
-  const render = component.render.bind(component);
-  component.render = function(...args) {
-    console.log(`[DEBUG] render: '${name}<id=${id}>'`);
-    return render(...args);
-  };
-  const mount = component.mount.bind(component);
-  component.mount = function(...args) {
-    console.log(`[DEBUG] mount: '${name}<id=${id}>'`);
-    return mount(...args);
-  };
-}
-```
-
-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/tutorial_todoapp.md

@@ -297,7 +297,7 @@ A lot of stuff happened here:
 - the `Task` component has a `props` key: this is only useful for validation
   purpose. It says that each `Task` should be given exactly one prop, named
   `task`. If this is not the case, Owl will throw an
-  [error](../reference/component.md#props-validation). This is extremely
+  [error](../reference/props_validation.md). This is extremely
   useful when refactoring components
 - finally, to activate the props validation, we need to set Owl's
   [mode](../reference/config.md#mode) to `dev`. This is done in the `setup`

doc/readme.md

@@ -4,6 +4,7 @@
 
 - [Animations](reference/animations.md)
 - [Component](reference/component.md)
+- [Concurrency Model](reference/concurrency_model.md)
 - [Configuration](reference/config.md)
 - [Context](reference/context.md)
 - [Environment](reference/environment.md)
@@ -12,6 +13,7 @@
 - [Miscellaneous Components](reference/misc.md)
 - [Observer](reference/observer.md)
 - [Props](reference/props.md)
+- [Props Validation](reference/props_validation.md)
 - [QWeb Templating Language](reference/qweb_templating_language.md)
 - [QWeb Engine](reference/qweb_engine.md)
 - [Router](reference/router.md)
@@ -23,7 +25,7 @@
 
 - [Quick Start: create an (almost) empty Owl application](learning/quick_start.md)
 - [Tutorial: create a TodoList application](learning/tutorial_todoapp.md)
-- [Testing and Debugging Owl components](learning/testing_components.md)
+- [Testing Owl components](learning/testing_components.md)
 
 ## Miscellaneous
 
@@ -48,20 +50,20 @@ and `EventBus` is exported as `owl.core.EventBus`):
 ```
 Component                               misc
 Context                                     AsyncRoot
-QWeb                                    router
+QWeb                                        Portal
-Store                                       Link
+Store                                   router
-useState                                    RouteComponent
+useState                                    Link
-config                                      Router
+config                                      RouteComponent
-    mode                                tags
+    mode                                    Router
-core                                        xml
+core                                    tags
-    EventBus                            utils
+    EventBus                                xml
-    Observer                                debounce
+    Observer                            utils
-hooks                                       escape
+hooks                                       debounce
-    onWillStart                             loadJS
+    onWillStart                             escape
-    onMounted                               loadFile
+    onMounted                               loadJS
-    onWillUpdateProps                       shallowEqual
+    onWillUpdateProps                       loadFile
-    onWillPatch                             whenReady
+    onWillPatch                             shallowEqual
-    onPatched
+    onPatched                               whenReady
     onWillUnmount
     useContext
     useState

doc/reference/component.md

@@ -14,12 +14,9 @@
   - [Composition](#composition)
   - [Event Handling](#event-handling)
   - [Form Input Bindings](#form-input-bindings)
-  - [Semantics](#semantics)
-  - [Props Validation](#props-validation)
   - [References](#references)
   - [Slots](#slots)
   - [Dynamic sub components](#dynamic-sub-components)
-  - [Asynchronous Rendering](#asynchronous-rendering)
   - [Error Handling](#error-handling)
   - [Functional Components](#functional-components)
   - [SVG components](#svg-components)
@@ -204,7 +201,7 @@ to be called in the constructor.
 * **`props`** (Object, optional): if given, this is an object that describes the
   type and shape of the (actual) props given to the component. If Owl mode is
   `dev`, this will be used to validate the props each time the component is
-  created/updated. See [Props Validation](#props-validation) for more information.
+  created/updated. See [Props Validation](props_validation.md) for more information.
 
   ```js
   class Counter extends owl.Component {
@@ -745,196 +742,6 @@ update a number whenever the change is done.
 
 Note: the online playground has an example to show how it works.
 
-### Semantics
-
-We give here an informal description of the way components are created/updated
-in an application. Here, ordered lists describe actions that are executed
-sequentially, bullet lists describe actions that are executed in parallel.
-
-**Scenario 1: initial rendering** Imagine we want to render the following component tree:
-
-```
-        A
-       / \
-      B   C
-         / \
-        D   E
-```
-
-Here is what happen whenever we mount the root
-component (with some code like `app.mount(document.body)`).
-
-1. `willStart` is called on `A`
-
-2. when it is done, template `A` is rendered.
-
-   - component `B` is created
-     1. `willStart` is called on `B`
-     2. template `B` is rendered
-   - component `C` is created
-     1. `willStart` is called on `C`
-     2. template `C` is rendered
-        - component `D` is created
-          1. `willStart` is called on `D`
-          2. template `D` is rendered
-        - component `E` is created
-          1. `willStart` is called on `E`
-          2. template `E` is rendered
-
-3. each components are patched into a detached DOM element, in the following order:
-   `E`, `D`, `C`, `B`, `A`. (so the actual full DOM tree is created
-   in one pass)
-
-4. the component `A` root element is actually appended to `document.body`
-
-5. The method `mounted` is called recursively on all components in the following
-   order: `E`, `D`, `C`, `B`, `A`.
-
-**Scenario 2: rerendering a component**. Now, let's assume that the user clicked on some
-button in `C`, and this results in a state update, which is supposed to:
-
-- update `D`,
-- remove `E`,
-- add new component `F`.
-
-So, the component tree should look like this:
-
-```
-        A
-       / \
-      B   C
-         / \
-        D   F
-```
-
-Here is what Owl will do:
-
-1. because of a state change, the method `render` is called on `C`
-2. template `C` is rendered again
-
-   - component `D` is updated:
-     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)
-     2. template `F` is rendered
-
-3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,
-   because it is not mounted yet)
-
-4. components `F`, `D` are patched in that order
-
-5. component `C` is patched, which will cause recursively:
-
-   1. `willUnmount` hook on `E`
-   2. destruction of `E`,
-
-6. `mounted` hook is called on `F`, `patched` hooks are called on `D`, `C`
-
-### Props Validation
-
-As an application becomes complex, it may be quite unsafe to define props in an informal way. This leads to two issues:
-
-- hard to tell how a component should be used, by looking at its code.
-- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parents.
-
-A props type system solves both issues, by describing the types and shapes
-of the props. Here is how it works in Owl:
-
-- `props` key is a static key (so, different from `this.props` in a component instance)
-- it is optional: it is ok for a component to not define a `props` key.
-- props are validated whenever a component is created/updated
-- props are only validated in `dev` mode (see [config page](config.md#mode))
-- if a key does not match the description, an error is thrown
-- it validates keys defined in (static) `props`. Additional keys given by the
-  parent will cause an error.
-
-For example:
-
-```js
-class ComponentA extends owl.Component {
-    static props = ['id', 'url'];
-
-    ...
-}
-
-class ComponentB extends owl.Component {
-  static props = {
-    count: {type: Number},
-    messages: {
-      type: Array,
-      element: {type: Object, shape: {id: Boolean, text: 'string' }
-    },
-   date: Date,
-   combinedVal: [Number, Boolean]
-  };
-
-  ...
-}
-```
-
-- it is an object or a list of strings
-- a list of strings is a simplified props definition, which only lists the name
-  of the props. Also, if the name ends with `?`, it is considered optional.
-- all props are by default required, unless they are defined with `optional: true`
-  (in that case, validation is only done if there is a value)
-- valid types are: `Number, String, Boolean, Object, Array, Date, Function`, and all
-  constructor functions (so, if you have a `Person` class, it can be used as a type)
-- arrays are homogeneous (all elements have the same type/shape)
-
-For each key, a `prop` definition is either a boolean, a constructor, a list of constructors, or an object:
-
-- a boolean: indicate that the props exists, and is mandatory.
-- a constructor: this should describe the type, for example: `id: Number` describe
-  the props `id` as a number
-- a list of constructors. In that case, this means that we allow more than one
-  type. For example, `id: [Number, String]` means that `id` can be either a string
-  or a number.
-- an object. This makes it possible to have more expressive definition. The following sub keys are then allowed (but not mandatory):
-  - `type`: the main type of the prop being validated
-  - `element`: if the type was `Array`, then the `element` key describes the type of each element in the array. If it is not set, then we only validate the array, not its elements,
-  - `shape`: if the type was `Object`, then the `shape` key describes the interface of the object. If it is not set, then we only validate the object, not its elements,
-  - `validate`: this is a function which should return a boolean to determine if
-    the value is valid or not. Useful for custom validation logic.
-
-Examples:
-
-```js
-  // only the existence of those 3 keys is documented
-  static props = ['message', 'id', 'date'];
-```
-
-```js
-  // size is optional
-  static props = ['message', 'size?'];
-```
-
-```js
-  static props = {
-    messageIds: {type: Array, element: Number},  // list of number
-    otherArr: {type: Array},   // just array. no validation is made on sub elements
-    otherArr2: Array,   // same as otherArr
-    someObj: {type: Object},  // just an object, no internal validation
-    someObj2: {
-      type: Object,
-      shape: {
-        id: Number,
-        name: {type: String, optional: true},
-        url: String
-      ]},    // object, with keys id (number), name (string, optional) and url (string)
-    someFlag: Boolean,     // a boolean, mandatory (even if `false`)
-    someVal: [Boolean, Date],   // either a boolean or a date
-    otherValue: true,     // indicates that it is a prop
-    kindofsmallnumber: {
-      type: Number,
-      validate: n => (0 <= n && n <= 10)
-    },
-    size: {
-      validate:  e => ["small", "medium", "large"].includes(e)
-    },
-  };
-```
-
 ### References
 
 The `useRef` hook is useful when we need a way to interact with some inside part
@@ -1092,49 +899,6 @@ component class.
 
 Note that the `t-component` directive can only be used on `<t>` nodes.
 
-### Asynchronous Rendering
-
-Working with asynchronous code always adds a lot of complexity to a system. Whenever
-different parts of a system are active at the same time, one needs to think
-carefully about all possible interactions. Clearly, this is also true for Owl
-components.
-
-There are two different common problems with Owl asynchronous rendering model:
-
-- any component can delay the rendering (initial and subsequent) of the whole
-  application
-- for a given component, there are two independant situations that will trigger an
-  asynchronous rerendering: a change in the state, or a change in the props.
-  These changes may be done at different times, and Owl has no way of knowing
-  how to reconcile the resulting renderings.
-
-Here are a few tips on how to work with asynchronous components:
-
-1. Minimize the use of asynchronous components!
-2. Maybe move the asynchronous logic in a store, which then triggers (mostly)
-   synchronous renderings
-3. Lazy loading external libraries is a good use case for async rendering. This
-   is mostly fine, because we can assume that it will only takes a fraction of a
-   second, and only once (see [`owl.utils.loadJS`](utils.md#loadjs))
-4. For all the other cases, the [`AsyncRoot`](misc.md#asyncroot) component is there to help you. When
-   this component is met, a new rendering
-   sub tree is created, such that the rendering of that component (and its
-   children) is not tied to the rendering of the rest of the interface. It can
-   be used on an asynchronous component, to prevent it from delaying the
-   rendering of the whole interface, or on a synchronous one, such that its
-   rendering isn't delayed by other (asynchronous) components. Note that this
-   directive has no effect on the first rendering, but only on subsequent ones
-   (triggered by state or props changes).
-
-   ```xml
-   <div t-name="ParentComponent">
-     <SyncChild />
-     <AsyncRoot>
-        <AsyncChild/>
-     </AsyncRoot>
-   </div>
-   ```
-
 ### Error Handling
 
 By default, whenever an error occurs in the rendering of an Owl application, we

doc/reference/concurrency_model.md

@@ -0,0 +1,183 @@
+# 🦉 Concurrency Model 🦉
+
+## Content
+
+- [Overview](#overview)
+- [Rendering Components](#rendering-components)
+- [Semantics](#semantics)
+- [Asynchronous Rendering](#asynchronous-rendering)
+
+## Overview
+
+Owl was designed from the very beginning with asynchronous components. This comes
+from the `willStart` and the `willUpdateProps` lifecycle hooks. With these
+methods, it is possible to build complex highly concurrent applications.
+
+Owl concurrent mode has several benefits: it makes it possible to delay the
+rendering until some asynchronous operation is complete, it makes it possible
+to lazy load libraries, while keeping the previous screen completely functional.
+It is also good for performance reasons: Owl uses it to only apply the result of
+many different renderings only once in an animation frame. Owl can cancel
+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.
+
+## Rendering Components
+
+The word _rendering_ is a little vague, so, let us explain more precisely the
+process by which Owl components are displayed on a screen.
+
+When a component is mounted or updated, a new rendering is started. It has
+two phases: _virtual rendering_ and _patching_.
+
+### Virtual rendering
+
+This phase represent the process of rendering a template, in memory, which create a virtual representation of the desired component html). The output of this phase is a
+virtual DOM.
+
+It is asynchronous: each subcomponents needs to either be created (so, `willStart`
+will need to be called), or updated (which is done with the `willUpdateProps`
+method). This is completely a recursive process: a component is the root of a
+component tree, and each sub component needs to be (virtually) rendered.
+
+### Patching
+
+Once a rendering is complete, it will be applied on the next animation frame.
+This is done synchronously: the whole component tree is patched to the real
+DOM.
+
+## Semantics
+
+We give here an informal description of the way components are created/updated
+in an application. Here, ordered lists describe actions that are executed
+sequentially, bullet lists describe actions that are executed in parallel.
+
+**Scenario 1: initial rendering** Imagine we want to render the following component tree:
+
+```
+        A
+       / \
+      B   C
+         / \
+        D   E
+```
+
+Here is what happen whenever we mount the root
+component (with some code like `app.mount(document.body)`).
+
+1. `willStart` is called on `A`
+
+2. when it is done, template `A` is rendered.
+
+   - component `B` is created
+     1. `willStart` is called on `B`
+     2. template `B` is rendered
+   - component `C` is created
+     1. `willStart` is called on `C`
+     2. template `C` is rendered
+        - component `D` is created
+          1. `willStart` is called on `D`
+          2. template `D` is rendered
+        - component `E` is created
+          1. `willStart` is called on `E`
+          2. template `E` is rendered
+
+3. each components are patched into a detached DOM element, in the following order:
+   `E`, `D`, `C`, `B`, `A`. (so the actual full DOM tree is created
+   in one pass)
+
+4. the component `A` root element is actually appended to `document.body`
+
+5. The method `mounted` is called recursively on all components in the following
+   order: `E`, `D`, `C`, `B`, `A`.
+
+**Scenario 2: rerendering a component**. Now, let's assume that the user clicked on some
+button in `C`, and this results in a state update, which is supposed to:
+
+- update `D`,
+- remove `E`,
+- add new component `F`.
+
+So, the component tree should look like this:
+
+```
+        A
+       / \
+      B   C
+         / \
+        D   F
+```
+
+Here is what Owl will do:
+
+1. because of a state change, the method `render` is called on `C`
+2. template `C` is rendered again
+
+   - component `D` is updated:
+     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)
+     2. template `F` is rendered
+
+3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,
+   because it is not mounted yet)
+
+4. components `F`, `D` are patched in that order
+
+5. component `C` is patched, which will cause recursively:
+
+   1. `willUnmount` hook on `E`
+   2. destruction of `E`,
+
+6. `mounted` hook is called on `F`, `patched` hooks are called on `D`, `C`
+
+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).
+
+### Asynchronous Rendering
+
+Working with asynchronous code always adds a lot of complexity to a system. Whenever
+different parts of a system are active at the same time, one needs to think
+carefully about all possible interactions. Clearly, this is also true for Owl
+components.
+
+There are two different common problems with Owl asynchronous rendering model:
+
+- any component can delay the rendering (initial and subsequent) of the whole
+  application
+- for a given component, there are two independant situations that will trigger an
+  asynchronous rerendering: a change in the state, or a change in the props.
+  These changes may be done at different times, and Owl has no way of knowing
+  how to reconcile the resulting renderings.
+
+Here are a few tips on how to work with asynchronous components:
+
+1. Minimize the use of asynchronous components!
+2. Maybe move the asynchronous logic in a store, which then triggers (mostly)
+   synchronous renderings
+3. Lazy loading external libraries is a good use case for async rendering. This
+   is mostly fine, because we can assume that it will only takes a fraction of a
+   second, and only once (see [`owl.utils.loadJS`](utils.md#loadjs))
+4. For all the other cases, the [`AsyncRoot`](misc.md#asyncroot) component is there to help you. When
+   this component is met, a new rendering
+   sub tree is created, such that the rendering of that component (and its
+   children) is not tied to the rendering of the rest of the interface. It can
+   be used on an asynchronous component, to prevent it from delaying the
+   rendering of the whole interface, or on a synchronous one, such that its
+   rendering isn't delayed by other (asynchronous) components. Note that this
+   directive has no effect on the first rendering, but only on subsequent ones
+   (triggered by state or props changes).
+
+   ```xml
+   <div t-name="ParentComponent">
+     <SyncChild />
+     <AsyncRoot>
+        <AsyncChild/>
+     </AsyncRoot>
+   </div>
+   ```

doc/reference/misc.md

@@ -1,5 +1,116 @@
 # 🦉 Miscellaneous 🦉
 
+## Content
+
+- [Portal](#portal)
+- [AsyncRoot](#asyncroot)
+
+## `Portal`
+
+### Overview
+
+The component `Portal` is meant to be used as a transparent way to 'teleport' a piece
+of DOM to the node represented by its sole `target` props.
+
+This component aims at helping the implementation of the needed infrastructure
+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).
+
+This slot must contain only **one** node, which in turn can have as many children as necessary.
+
+The element under which the content will be teleported is represented as a selector
+by the `target` props which only accepts a string as value.
+
+The `target` props only supports static selector, and is not meant to be passed to `Portal`
+as a variable. Namely, `<Portal target="'body'" />` is the intended use.
+By contrast, `<Portal target="state.target" />` is not supported.
+
+The component `Portal` has no particular state, rather it is meant to be a slave to its parent,
+and ultimately just a way for the parent to teleport a piece of its own DOM elsewhere.
+
+The `Portal`'s root node is always `<portal/>` and is placed where the teleported content
+_would have_ been. It is this element that the [teleported events](#expected-behaviors) are re-directed on.
+
+### Example
+
+The canonic use-case is to implement a Dialog, where a Component may choose to break the natural
+workflow to help the user put in some data, which it could use later on.
+
+JavaScript:
+
+```js
+const { Component } = owl;
+const { Portal } = owl.misc;
+
+class TeleportedComponent extends Component {}
+class App extends Component {
+  static components = { Portal, TeleportedComponent };
+}
+
+const app = new App();
+app.mount(document.body);
+```
+
+XML:
+
+```xml
+<templates>
+    <div t-name="TeleportedComponent">
+        <span>I will move soon enough</span>
+    </div>
+
+    <div t-name="App">
+        <span>I am like the rest of us</span>
+        <Portal target="'body'">
+            <TeleportedComponent />
+        </Portal>
+    </div>
+</templates>
+```
+
+In this example, the `Portal` component will teleport the `TeleportedComponent`'s `div` as a child of the `body`.
+`TeleportedComponent` is acting as a Dialog here.
+
+The resulting DOM will look like:
+
+```xml
+<body>
+    <div>
+        <span>I am like the rest of us</span>
+        <portal></portal>
+    </div>
+    <div>
+        <span>I will move soon enough</span>
+    </div>
+</body>
+```
+
+### Expected Behaviors
+
+The teleported piece is updated as any other `Component`'s DOM and in the same sequence.
+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
+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.
+
+Beware that those re-directed events are copies of the original event.
+They have:
+
+- The same payload.
+- The same `originalComponent` than their original counterpart,
+  that is the actual Component that triggered it.
+- A **different** `target` property than their original counterpart.
+  The `target` of a re-directed event is necessarily the `Portal`'s root node.
+
+Pure DOM events do not follow this pattern and are free to bubble their natural, unaltered way
+up to the `body`.
+
 ## `AsyncRoot`
 
 When this component is used, a new rendering sub tree is created, such that the

doc/reference/props_validation.md

@@ -0,0 +1,103 @@
+# 🦉 Props Validation 🦉
+
+As an application becomes complex, it may be quite unsafe to define props in an informal way. This leads to two issues:
+
+- hard to tell how a component should be used, by looking at its code.
+- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parents.
+
+A props type system solves both issues, by describing the types and shapes
+of the props. Here is how it works in Owl:
+
+- `props` key is a static key (so, different from `this.props` in a component instance)
+- it is optional: it is ok for a component to not define a `props` key.
+- props are validated whenever a component is created/updated
+- props are only validated in `dev` mode (see [config page](config.md#mode))
+- if a key does not match the description, an error is thrown
+- it validates keys defined in (static) `props`. Additional keys given by the
+  parent will cause an error.
+
+For example:
+
+```js
+class ComponentA extends owl.Component {
+    static props = ['id', 'url'];
+
+    ...
+}
+
+class ComponentB extends owl.Component {
+  static props = {
+    count: {type: Number},
+    messages: {
+      type: Array,
+      element: {type: Object, shape: {id: Boolean, text: 'string' }
+    },
+   date: Date,
+   combinedVal: [Number, Boolean]
+  };
+
+  ...
+}
+```
+
+- it is an object or a list of strings
+- a list of strings is a simplified props definition, which only lists the name
+  of the props. Also, if the name ends with `?`, it is considered optional.
+- all props are by default required, unless they are defined with `optional: true`
+  (in that case, validation is only done if there is a value)
+- valid types are: `Number, String, Boolean, Object, Array, Date, Function`, and all
+  constructor functions (so, if you have a `Person` class, it can be used as a type)
+- arrays are homogeneous (all elements have the same type/shape)
+
+For each key, a `prop` definition is either a boolean, a constructor, a list of constructors, or an object:
+
+- a boolean: indicate that the props exists, and is mandatory.
+- a constructor: this should describe the type, for example: `id: Number` describe
+  the props `id` as a number
+- a list of constructors. In that case, this means that we allow more than one
+  type. For example, `id: [Number, String]` means that `id` can be either a string
+  or a number.
+- an object. This makes it possible to have more expressive definition. The following sub keys are then allowed (but not mandatory):
+  - `type`: the main type of the prop being validated
+  - `element`: if the type was `Array`, then the `element` key describes the type of each element in the array. If it is not set, then we only validate the array, not its elements,
+  - `shape`: if the type was `Object`, then the `shape` key describes the interface of the object. If it is not set, then we only validate the object, not its elements,
+  - `validate`: this is a function which should return a boolean to determine if
+    the value is valid or not. Useful for custom validation logic.
+
+Examples:
+
+```js
+  // only the existence of those 3 keys is documented
+  static props = ['message', 'id', 'date'];
+```
+
+```js
+  // size is optional
+  static props = ['message', 'size?'];
+```
+
+```js
+  static props = {
+    messageIds: {type: Array, element: Number},  // list of number
+    otherArr: {type: Array},   // just array. no validation is made on sub elements
+    otherArr2: Array,   // same as otherArr
+    someObj: {type: Object},  // just an object, no internal validation
+    someObj2: {
+      type: Object,
+      shape: {
+        id: Number,
+        name: {type: String, optional: true},
+        url: String
+      ]},    // object, with keys id (number), name (string, optional) and url (string)
+    someFlag: Boolean,     // a boolean, mandatory (even if `false`)
+    someVal: [Boolean, Date],   // either a boolean or a date
+    otherValue: true,     // indicates that it is a prop
+    kindofsmallnumber: {
+      type: Number,
+      validate: n => (0 <= n && n <= 10)
+    },
+    size: {
+      validate:  e => ["small", "medium", "large"].includes(e)
+    },
+  };
+```

doc/tooling.md

@@ -6,6 +6,7 @@
 - [Playground](#playground)
 - [Benchmarks](#benchmarks)
 - [Single File Component](#single-file-component)
+- [Debugging Script](#debugging-script)
 
 ## Overview
 
@@ -78,3 +79,28 @@ 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(o,t){let e,n="[OWL_DEBUG]";function l(o){let t=JSON.stringify(o||{});return t.length>200&&(t=t.slice(0,200)+"..."),t}if(Object.defineProperty(o.Component,"current",{get:()=>e,set(s){e=s;const c=s.constructor.name;if(t.componentBlackList&&t.componentBlackList.test(c))return;if(t.componentWhiteList&&!t.componentWhiteList.test(c))return;let r;Object.defineProperty(e,"__owl__",{get:()=>r,set(e){!function(e,s,c){let r=`${s}<id=${c}>`,i=o=>(!t.methodBlackList||!t.methodBlackList.includes(o))&&!(t.methodWhiteList&&!t.methodWhiteList.includes(o));i("constructor")&&console.log(`${n} ${r} constructor, props=${l(e.props)}`);i("willStart")&&o.hooks.onWillStart(()=>{console.log(`${n} ${r} willStart`)});i("mounted")&&o.hooks.onMounted(()=>{console.log(`${n} ${r} mounted`)});i("willUpdateProps")&&o.hooks.onWillUpdateProps(o=>{console.log(`${n} ${r} willUpdateProps, nextprops=${l(o)}`)});i("willPatch")&&o.hooks.onWillPatch(()=>{console.log(`${n} ${r} willPatch`)});i("patched")&&o.hooks.onPatched(()=>{console.log(`${n} ${r} patched`)});i("willUnmount")&&o.hooks.onWillUnmount(()=>{console.log(`${n} ${r} willUnmount`)});const u=e.__render.bind(e);e.__render=function(...o){console.log(`${n} ${r} rendering template`),u(...o)};const d=e.render.bind(e);e.render=function(...o){return console.log(`${n} ${r} render`),d(...o)};const p=e.mount.bind(e);e.mount=function(...o){return console.log(`${n} ${r} mount`),p(...o)}}(s,c,(r=e).id)}})}}),t.logScheduler){let t=o.Component.scheduler.start,e=o.Component.scheduler.stop;o.Component.scheduler.start=function(){console.log(`${n} scheduler: start running tasks queue`),t.call(this)},o.Component.scheduler.stop=function(){console.log(`${n} scheduler: stop running tasks queue`),e.call(this)}}if(t.logStore){let t=o.Store.prototype.dispatch;o.Store.prototype.dispatch=function(o,...e){return console.log(`${n} store: action '${o}' dispatched. Payload: '${l(e)}'`),t.call(this,o,...e)}}}
+debugOwl({
+  // 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

@@ -1,6 +1,6 @@
 {
   "name": "owl-framework",
-  "version": "1.0.0-alpha5",
+  "version": "1.0.0-beta1",
   "description": "Odoo Web Library (OWL)",
   "main": "src/index.ts",
   "engines": {

roadmap.md

@@ -1,25 +1,17 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.0.0-alpha5
+- Current version: 1.0.0-beta1
 - Status: mostly stable
 
 This roadmap is only an attempt at predicting Owl's future.  Everything may
 change!
 
 
-### November 2019
-
-Owl will be used in various Odoo projects. We plan to:
-
-- fix any issues encountered
-- maybe cleanup slightly the router API
-- improve the documentation
-- improve error handling, add more helpful error messages
 
 ### December 2019
 
-If all goes well, Owl will be upgraded to beta status. From then, no API change,
+If all goes well, Owl is upgraded to beta status. From now on, no API change,
-even small, is expected.
+even small, is expected (but it still could happen).
 
 ### End of 2019
 
@@ -41,7 +33,8 @@ Release v1.0
 
 Maybe:
 
-- reimplement vdom to use *block* system, like Vue 3,
+- reimplement vdom to use *block* system, like Vue 3, which should make Owl
+  much faster
 - refactor `QWeb` to use an intermediate representation (some kind of AST) to
   allow additional optimisations.
 

src/component/component.ts

@@ -84,6 +84,8 @@ interface Internal<T extends Env, Props> {
   refs: { [key: string]: Component<T, any> | HTMLElement | undefined } | null;
 }
 
+export const portalSymbol = Symbol("portal"); // FIXME
+
 //------------------------------------------------------------------------------
 // Component
 //------------------------------------------------------------------------------
@@ -302,7 +304,7 @@ export class Component<T extends Env, Props extends {}> {
     const fiber = new Fiber(null, this, false, target);
     fiber.shouldPatch = false;
     if (!__owl__.vnode) {
-      this.__prepareAndRender(fiber);
+      this.__prepareAndRender(fiber, () => {});
     } else {
       this.__render(fiber);
     }
@@ -397,14 +399,7 @@ export class Component<T extends Env, Props extends {}> {
    * willUnmount().
    */
   trigger(eventType: string, payload?: any) {
-    if (this.el) {
+    this.__trigger(this, eventType, payload);
-      const ev = new OwlEvent(this, eventType, {
-        bubbles: true,
-        cancelable: true,
-        detail: payload
-      });
-      this.el.dispatchEvent(ev);
-    }
   }
 
   //--------------------------------------------------------------------------
@@ -478,7 +473,24 @@ 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) {
+    if (this.el) {
+      const ev = new OwlEvent(component, eventType, {
+        bubbles: true,
+        cancelable: true,
+        detail: payload
+      });
+      const triggerHook = this.env[portalSymbol as any];
+      if (triggerHook) {
+        triggerHook(ev);
+      }
+      this.el.dispatchEvent(ev);
+    }
+  }
   /**
    * The __updateProps method is called by the t-component directive whenever
    * it updates a component (so, when the parent template is rerendered).
@@ -532,7 +544,7 @@ export class Component<T extends Env, Props extends {}> {
    * subcomponent is created. It gets its scope and vars, if any, from the
    * parent template.
    */
-  __prepare(parentFiber: Fiber, scope: any, vars: any) {
+  __prepare(parentFiber: Fiber, scope: any, vars: any, cb: CallableFunction): Fiber {
     this.__owl__.scope = scope;
     this.__owl__.vars = vars;
     const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
@@ -543,7 +555,8 @@ export class Component<T extends Env, Props extends {}> {
       parentFiber.lastChild!.sibling = fiber;
     }
     parentFiber.lastChild = fiber;
-    return this.__prepareAndRender(fiber);
+    this.__prepareAndRender(fiber, cb);
+    return fiber;
   }
 
   __getTemplate(qweb: QWeb): string {
@@ -565,7 +578,7 @@ export class Component<T extends Env, Props extends {}> {
     }
     return p._template;
   }
-  async __prepareAndRender(fiber: Fiber) {
+  async __prepareAndRender(fiber: Fiber, cb: CallableFunction) {
     try {
       await Promise.all([this.willStart(), this.__owl__.willStartCB && this.__owl__.willStartCB()]);
     } catch (e) {
@@ -577,6 +590,7 @@ export class Component<T extends Env, Props extends {}> {
     }
     if (!fiber.isCompleted) {
       this.__render(fiber);
+      cb();
     }
   }
 

src/component/directive.ts

@@ -226,7 +226,6 @@ QWeb.addDirective({
     let propStr = Object.keys(props)
       .map(k => k + ":" + props[k])
       .join(",");
-    let defID = ctx.generateID();
     let componentID = ctx.generateID();
 
     const templateKey = ctx.generateTemplateKey();
@@ -439,16 +438,14 @@ QWeb.addDirective({
       }
     }
 
-    ctx.addLine(`let def${defID} = w${componentID}.__prepare(extra.fiber, ${scopeVars});`);
+    ctx.addLine(
+      `let fiber = w${componentID}.__prepare(extra.fiber, ${scopeVars}, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
+    );
     // hack: specify empty remove hook to prevent the node from being removed from the DOM
     const insertHook = refExpr ? `insert(vn) {${refExpr}},` : "";
     ctx.addLine(
       `let pvnode = h('dummy', {key: ${templateKey}, hook: {${insertHook}remove() {},destroy(vn) {${finalizeComponentCode}}}});`
     );
-    ctx.addLine(`const fiber = w${componentID}.__owl__.currentFiber;`);
-    ctx.addLine(
-      `def${defID}.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
-    );
     if (registerCode) {
       ctx.addLine(registerCode);
     }

src/component/fiber.ts

@@ -222,6 +222,7 @@ export class Fiber {
     if (this.target) {
       this.target.appendChild(this.component.el!);
       inDOM = document.body.contains(this.target);
+      this.component.env.qweb.trigger("dom-appended");
     }
 
     // call patched/mounted hook on each fiber of (reversed) patchQueue

src/component/scheduler.ts

@@ -25,6 +25,15 @@ export class Scheduler {
     this.requestAnimationFrame = requestAnimationFrame;
   }
 
+  start() {
+    this.isRunning = true;
+    this.scheduleTasks();
+  }
+
+  stop() {
+    this.isRunning = false;
+  }
+
   addFiber(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
@@ -43,7 +52,7 @@ export class Scheduler {
         }
       });
       if (!this.isRunning) {
-        this.scheduleTasks();
+        this.start();
       }
     });
   }
@@ -74,16 +83,16 @@ export class Scheduler {
       return true;
     });
     this.tasks = tasks.concat(this.tasks);
+    if (this.tasks.length === 0) {
+      this.stop();
+    }
   }
 
   scheduleTasks() {
-    this.isRunning = true;
     this.requestAnimationFrame(() => {
       this.flush();
-      if (this.tasks.length > 0) {
+      if (this.isRunning) {
         this.scheduleTasks();
-      } else {
-        this.isRunning = false;
       }
     });
   }

src/index.ts

@@ -12,6 +12,7 @@ import * as _store from "./store";
 import * as _utils from "./utils";
 import * as _tags from "./tags";
 import { AsyncRoot } from "./misc/async_root";
+import { Portal } from "./misc/portal";
 import * as _hooks from "./hooks";
 import * as _context from "./context";
 import { Link } from "./router/link";
@@ -29,7 +30,7 @@ export const router = { Router, RouteComponent, Link };
 export const Store = _store.Store;
 export const utils = _utils;
 export const tags = _tags;
-export const misc = { AsyncRoot };
+export const misc = { AsyncRoot, Portal };
 export const hooks = Object.assign({}, _hooks, {
   useContext: _context.useContext,
   useDispatch: _store.useDispatch,

src/misc/portal.ts

@@ -0,0 +1,156 @@
+import { Component, portalSymbol } from "../component/component";
+import { VNode, patch } from "../vdom/index";
+import { xml } from "../tags";
+import { OwlEvent } from "../core/owl_event";
+import { useSubEnv } from "../hooks";
+
+/**
+ * Portal
+ *
+ * The Portal component allows to render a part of a component outside it's DOM.
+ * It is for example useful for dialogs: for css reasons, dialogs are in general
+ * placed in a specific spot of the DOM (e.g. directly in the body). With the
+ * Portal, a component can conditionally specify in its tempate that it contains
+ * a dialog, and where this dialog should be inserted in the DOM.
+ *
+ * The Portal component ensures that the communication between the content of
+ * the Portal and its parent properly works: business events reaching the Portal
+ * are re-triggered on an empty <portal> node located in the parent's DOM.
+ */
+
+export class Portal extends Component<any, any> {
+  static template = xml`<portal><t t-slot="default"/></portal>`;
+  static props = {
+    target: {
+      type: String
+    }
+  };
+
+  // boolean to indicate whether or not we must listen to 'dom-appended' event
+  // to hook on the moment when the target is inserted into the DOM (because it
+  // is not when the portal is rendered)
+  doTargetLookUp: boolean = true;
+  // set of encountered events that need to be redirected
+  _handledEvents: Set<string> = new Set();
+  // function that will be the event's tunnel (needs to be an arrow function to
+  // avoid having to rebind `this`)
+  _handlerTunnel: (f: OwlEvent<any>) => void = (ev: OwlEvent<any>) => {
+    ev.stopPropagation();
+    this.__trigger(ev.originalComponent, ev.type, ev.detail);
+  };
+  // Storing the parent's env
+  parentEnv: any = null;
+  // represents the element that is moved somewhere else
+  portal: VNode | null = null;
+  // the target where we will move `portal`
+  target: HTMLElement | null = null;
+
+  constructor(parent, props) {
+    super(parent, props);
+    this.parentEnv = parent ? parent.env : {};
+    // 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 => {
+        if (!this._handledEvents.has(ev.type)) {
+          this.portal!.elm!.addEventListener(ev.type, this._handlerTunnel);
+          this._handledEvents.add(ev.type);
+        }
+      }
+    });
+  }
+  /**
+   * At each DOM change, we must ensure that the portal contains exactly one
+   * child
+   */
+  __checkVNodeStructure(vnode: VNode) {
+    const children = vnode.children!;
+    let countRealNodes = 0;
+    for (let child of children) {
+      if ((child as VNode).sel) {
+        countRealNodes++;
+      }
+    }
+    if (countRealNodes !== 1) {
+      throw new Error(`Portal must have exactly one non-text child (has ${countRealNodes})`);
+    }
+  }
+  /**
+   * Ensure the target is still there at whichever time we render
+   */
+  __checkTargetPresence() {
+    if (!this.target || !document.contains(this.target)) {
+      throw new Error(`Could not find any match for "${this.props.target}"`);
+    }
+  }
+  /**
+   * Move the portal's element to the target
+   */
+  __deployPortal() {
+    this.__checkTargetPresence();
+    this.target!.appendChild(this.portal!.elm!);
+  }
+  /**
+   * Override to remove from the DOM the element we have teleported
+   *
+   * @override
+   */
+  __destroy(parent) {
+    if (this.portal && this.portal.elm) {
+      const displacedElm = this.portal.elm!;
+      const parent = displacedElm.parentNode;
+      if (parent) {
+        parent.removeChild(displacedElm);
+      }
+    }
+    super.__destroy(parent);
+  }
+  /**
+   * Override to patch the element that has been teleported
+   *
+   * @override
+   */
+  __patch(vnode) {
+    if (this.doTargetLookUp) {
+      const target = document.querySelector(this.props.target);
+      if (!target) {
+        this.env.qweb.on("dom-appended", this, () => {
+          this.doTargetLookUp = false;
+          this.env.qweb.off("dom-appended", this);
+          this.target = document.querySelector(this.props.target);
+          this.__deployPortal();
+        });
+      } else {
+        this.doTargetLookUp = false;
+        this.target = target;
+      }
+    }
+    this.__checkVNodeStructure(vnode);
+    const shouldDeploy = !this.portal && !this.doTargetLookUp;
+
+    if (!this.doTargetLookUp && !shouldDeploy) {
+      // Only on pure patching, provided the
+      // this.target's parent has not been unmounted
+      this.__checkTargetPresence();
+    }
+
+    const portalPatch = this.portal ? this.portal : document.createElement(vnode.children[0].sel);
+    this.portal = patch(portalPatch, vnode.children![0] as VNode);
+    vnode.children = [];
+
+    super.__patch(vnode);
+
+    if (shouldDeploy) {
+      this.__deployPortal();
+    }
+  }
+  /**
+   * Override to set the env
+   */
+  __trigger(component: Component<any, any>, eventType: string, payload?: any) {
+    const env = this.env;
+    this.env = this.parentEnv;
+    super.__trigger(component, eventType, payload);
+    this.env = env;
+  }
+}

tests/__snapshots__/animations.test.ts.snap

@@ -11,37 +11,35 @@ exports[`animations t-transition combined with component 1`] = `
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let k4 = \`__5__\`;
+    let k3 = \`__4__\`;
-    let w3 = k4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k4]] : false;
+    let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-    let props3 = {};
+    let props2 = {};
-    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-        w3.destroy();
+        w2.destroy();
-        w3 = false;
+        w2 = false;
     }
-    if (w3) {
+    if (w2) {
-        w3.__updateProps(props3, extra.fiber, undefined, undefined);
+        w2.__updateProps(props2, extra.fiber, undefined, undefined);
-        let pvnode = w3.__owl__.pvnode;
+        let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
-        let componentKey3 = \`Child\`;
+        let componentKey2 = \`Child\`;
-        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| context['Child'];
-        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-        w3 = new W3(parent, props3);
+        w2 = new W2(parent, props2);
-        const __patch3 = w3.__patch;
+        const __patch2 = w2.__patch;
-        w3.__patch = fiber => {__patch3.call(w3, fiber); if(!w3.__owl__.transitionInserted){w3.__owl__.transitionInserted = true;utils.transitionInsert(w3.__owl__.vnode, 'chimay');}};
+        w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-        parent.__owl__.cmap[k4] = w3.__owl__.id;
+        parent.__owl__.cmap[k3] = w2.__owl__.id;
-        let def2 = w3.__prepare(extra.fiber, undefined, undefined);
+        let fiber = w2.__prepare(extra.fiber, undefined, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-        let pvnode = h('dummy', {key: k4, hook: {remove() {},destroy(vn) {let finalize = () => {
+        let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w3.destroy();
+          w2.destroy();
         };
-        delete w3.__owl__.transitionInserted;
+        delete w2.__owl__.transitionInserted;
         utils.transitionRemove(vn, 'chimay', finalize);}}});
-        const fiber = w3.__owl__.currentFiber;
-        def2.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         c1.push(pvnode);
-        w3.__owl__.pvnode = pvnode;
+        w2.__owl__.pvnode = pvnode;
     }
-    w3.__owl__.parentLastFiberId = extra.fiber.id;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
     return vn1;
 }"
 `;
@@ -58,37 +56,35 @@ exports[`animations t-transition combined with t-component and t-if 1`] = `
     var vn1 = h('div', p1, c1);
     if (context['state'].display) {
         //COMPONENT
-        let k4 = \`__5__\`;
+        let k3 = \`__4__\`;
-        let w3 = k4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k4]] : false;
+        let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-        let props3 = {};
+        let props2 = {};
-        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+        if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-            w3.destroy();
+            w2.destroy();
-            w3 = false;
+            w2 = false;
         }
-        if (w3) {
+        if (w2) {
-            w3.__updateProps(props3, extra.fiber, undefined, undefined);
+            w2.__updateProps(props2, extra.fiber, undefined, undefined);
-            let pvnode = w3.__owl__.pvnode;
+            let pvnode = w2.__owl__.pvnode;
             c1.push(pvnode);
         } else {
-            let componentKey3 = \`Child\`;
+            let componentKey2 = \`Child\`;
-            let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| context['Child'];
-            if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+            if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-            w3 = new W3(parent, props3);
+            w2 = new W2(parent, props2);
-            const __patch3 = w3.__patch;
+            const __patch2 = w2.__patch;
-            w3.__patch = fiber => {__patch3.call(w3, fiber); if(!w3.__owl__.transitionInserted){w3.__owl__.transitionInserted = true;utils.transitionInsert(w3.__owl__.vnode, 'chimay');}};
+            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-            parent.__owl__.cmap[k4] = w3.__owl__.id;
+            parent.__owl__.cmap[k3] = w2.__owl__.id;
-            let def2 = w3.__prepare(extra.fiber, undefined, undefined);
+            let fiber = w2.__prepare(extra.fiber, undefined, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k4, hook: {remove() {},destroy(vn) {let finalize = () => {
+            let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w3.destroy();
+          w2.destroy();
         };
-        delete w3.__owl__.transitionInserted;
+        delete w2.__owl__.transitionInserted;
         utils.transitionRemove(vn, 'chimay', finalize);}}});
-            const fiber = w3.__owl__.currentFiber;
-            def2.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
             c1.push(pvnode);
-            w3.__owl__.pvnode = pvnode;
+            w2.__owl__.pvnode = pvnode;
         }
-        w3.__owl__.parentLastFiberId = extra.fiber.id;
+        w2.__owl__.parentLastFiberId = extra.fiber.id;
     }
     return vn1;
 }"
@@ -106,37 +102,35 @@ exports[`animations t-transition combined with t-component, remove and re-add be
     var vn1 = h('div', p1, c1);
     if (context['state'].flag) {
         //COMPONENT
-        let k4 = \`__5__\`;
+        let k3 = \`__4__\`;
-        let w3 = k4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k4]] : false;
+        let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-        let props3 = {};
+        let props2 = {};
-        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+        if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-            w3.destroy();
+            w2.destroy();
-            w3 = false;
+            w2 = false;
         }
-        if (w3) {
+        if (w2) {
-            w3.__updateProps(props3, extra.fiber, undefined, undefined);
+            w2.__updateProps(props2, extra.fiber, undefined, undefined);
-            let pvnode = w3.__owl__.pvnode;
+            let pvnode = w2.__owl__.pvnode;
             c1.push(pvnode);
         } else {
-            let componentKey3 = \`Child\`;
+            let componentKey2 = \`Child\`;
-            let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| context['Child'];
-            if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+            if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-            w3 = new W3(parent, props3);
+            w2 = new W2(parent, props2);
-            const __patch3 = w3.__patch;
+            const __patch2 = w2.__patch;
-            w3.__patch = fiber => {__patch3.call(w3, fiber); if(!w3.__owl__.transitionInserted){w3.__owl__.transitionInserted = true;utils.transitionInsert(w3.__owl__.vnode, 'chimay');}};
+            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-            parent.__owl__.cmap[k4] = w3.__owl__.id;
+            parent.__owl__.cmap[k3] = w2.__owl__.id;
-            let def2 = w3.__prepare(extra.fiber, undefined, undefined);
+            let fiber = w2.__prepare(extra.fiber, undefined, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k4, hook: {remove() {},destroy(vn) {let finalize = () => {
+            let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w3.destroy();
+          w2.destroy();
         };
-        delete w3.__owl__.transitionInserted;
+        delete w2.__owl__.transitionInserted;
         utils.transitionRemove(vn, 'chimay', finalize);}}});
-            const fiber = w3.__owl__.currentFiber;
-            def2.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
             c1.push(pvnode);
-            w3.__owl__.pvnode = pvnode;
+            w2.__owl__.pvnode = pvnode;
         }
-        w3.__owl__.parentLastFiberId = extra.fiber.id;
+        w2.__owl__.parentLastFiberId = extra.fiber.id;
     }
     return vn1;
 }"

tests/animations.test.ts

@@ -254,11 +254,11 @@ describe("animations", () => {
     widget.state.display = false;
     patchNextFrame(cb => {
       expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="__5__">blue</span></div>'
+        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="__4__">blue</span></div>'
       );
       cb();
       expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__5__">blue</span></div>'
+        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__4__">blue</span></div>'
       );
       def.resolve();
     });
@@ -371,7 +371,7 @@ describe("animations", () => {
 
     await def; // wait for the mocked repaint to be done
     widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend")); // mock end of css transition
-    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__5__">blue</span></div>');
+    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__4__">blue</span></div>');
   });
 
   test("transitionInsert is called the correct amount of times", async () => {
@@ -405,14 +405,14 @@ describe("animations", () => {
     widget.state.flag = false;
     await nextTick();
     expect(fixture.innerHTML).toBe(
-      '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__5__">blue</span></div>'
+      '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__4__">blue</span></div>'
     );
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(1);
 
     widget.state.flag = true;
     await nextTick();
     expect(fixture.innerHTML).toBe(
-      '<div><span class="chimay-enter-active chimay-enter-to" data-owl-key="__5__">blue</span></div>'
+      '<div><span class="chimay-enter-active chimay-enter-to" data-owl-key="__4__">blue</span></div>'
     );
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(2);
 
@@ -423,7 +423,7 @@ describe("animations", () => {
 
     expect(QWeb.utils.transitionInsert).toBeCalledTimes(3);
     widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend"));
-    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__5__">blue</span></div>');
+    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__4__">blue</span></div>');
     QWeb.utils.transitionInsert = oldTransitionInsert;
   });
 });

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

@@ -11,31 +11,29 @@ exports[`props validation props are validated in dev mode (code snapshot) 1`] =
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let k4 = \`__5__\`;
+    let k3 = \`__4__\`;
-    let w3 = k4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k4]] : false;
+    let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-    let props3 = {message:1};
+    let props2 = {message:1};
-    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-        w3.destroy();
+        w2.destroy();
-        w3 = false;
+        w2 = false;
     }
-    if (w3) {
+    if (w2) {
-        w3.__updateProps(props3, extra.fiber, undefined, undefined);
+        w2.__updateProps(props2, extra.fiber, undefined, undefined);
-        let pvnode = w3.__owl__.pvnode;
+        let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
-        let componentKey3 = \`Child\`;
+        let componentKey2 = \`Child\`;
-        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
+        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| context['Child'];
-        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-        w3 = new W3(parent, props3);
+        w2 = new W2(parent, props2);
-        parent.__owl__.cmap[k4] = w3.__owl__.id;
+        parent.__owl__.cmap[k3] = w2.__owl__.id;
-        let def2 = w3.__prepare(extra.fiber, undefined, undefined);
+        let fiber = w2.__prepare(extra.fiber, undefined, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-        let pvnode = h('dummy', {key: k4, hook: {remove() {},destroy(vn) {w3.destroy();}}});
+        let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {w2.destroy();}}});
-        const fiber = w3.__owl__.currentFiber;
-        def2.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         c1.push(pvnode);
-        w3.__owl__.pvnode = pvnode;
+        w2.__owl__.pvnode = pvnode;
     }
-    w3.__owl__.parentLastFiberId = extra.fiber.id;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
     return vn1;
 }"
 `;

tests/component/component.test.ts

@@ -1849,6 +1849,38 @@ describe("other directives with t-component", () => {
     expect(widget.n).toBe(1);
   });
 
+  test("t-on works, even if flush is called many times", async () => {
+    let flag = false;
+    let mounted = false;
+    class Child extends Component<any, any> {
+      static template = xml`<span>child</span>`;
+      mounted() {
+        mounted = true;
+      }
+    }
+
+    class Parent extends Component<any, any> {
+      static template = xml`<div><Child t-on-click="doSomething"/></div>`;
+      static components = { Child };
+
+      doSomething() {
+        flag = true;
+      }
+    }
+
+    const parent = new Parent();
+    parent.mount(fixture);
+    while (!mounted) {
+      await nextMicroTick();
+      Component.scheduler.flush();
+    }
+
+    expect(fixture.innerHTML).toBe("<div><span>child</span></div>");
+    expect(flag).toBe(false);
+    fixture.querySelector("span")!.click();
+    expect(flag).toBe(true);
+  });
+
   test("t-on with handler bound to argument", async () => {
     expect.assertions(3);
     env.qweb.addTemplates(`
@@ -2165,28 +2197,28 @@ describe("other directives with t-component", () => {
         grandChild = this;
       }
       _onEv() {
-        steps.push('GrandChild');
+        steps.push("GrandChild");
       }
     }
     class Child extends Component<any, any> {
       static template = xml`<GrandChild t-on-ev="_onEv"/>`;
       static components = { GrandChild };
       _onEv() {
-        steps.push('Child');
+        steps.push("Child");
       }
     }
     class Parent extends Component<any, any> {
       static template = xml`<Child t-on-ev="_onEv"/>`;
       static components = { Child };
       _onEv() {
-        steps.push('Parent');
+        steps.push("Parent");
       }
     }
     const parent = new Parent();
     await parent.mount(fixture);
 
     grandChild.trigger("ev");
-    expect(steps).toEqual(['GrandChild', 'Child', 'Parent']);
+    expect(steps).toEqual(["GrandChild", "Child", "Parent"]);
   });
 
   test("t-if works with t-component", async () => {

tests/misc/portal.test.ts

@@ -0,0 +1,828 @@
+import { Portal } from "../../src/misc/portal";
+import { xml } from "../../src/tags";
+import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
+import { Component } from "../../src/component/component";
+import { useState } from "../../src/hooks";
+import { QWeb } from "../../src/qweb";
+
+//------------------------------------------------------------------------------
+// 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.
+// - outside: a div with id #outside appended into fixture, meant to be used as
+//   target by Portal component
+// - a test env, necessary to create components, that is set on Component
+
+let fixture: HTMLElement;
+let outside: HTMLElement;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  outside = document.createElement("div");
+  outside.setAttribute("id", "outside");
+  fixture.appendChild(outside);
+
+  Component.env = makeTestEnv();
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+describe("Portal: Props validation", () => {
+  test("target is mandatory", async () => {
+    const dev = QWeb.dev;
+    QWeb.dev = true;
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal>
+            <div>2</div>
+          </Portal>
+        </div>`;
+    }
+    let error;
+    try {
+      const parent = new Parent();
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe(`Missing props 'target' (component 'Portal')`);
+
+    QWeb.dev = dev;
+  });
+
+  test("target is not list", async () => {
+    const dev = QWeb.dev;
+    QWeb.dev = true;
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="['body']">
+            <div>2</div>
+          </Portal>
+        </div>`;
+    }
+    let error;
+    try {
+      const parent = new Parent();
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe(`Invalid Prop 'target' in component 'Portal'`);
+
+    QWeb.dev = dev;
+  });
+});
+
+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> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <span>1</span>
+          <Portal target="'#outside'">
+            <div>2</div>
+          </Portal>
+        </div>`;
+    }
+    let error;
+    let parent;
+    try {
+      parent = new Parent();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeUndefined();
+    await parent.mount(fixture);
+    expect(outside.innerHTML).toBe("<div>2</div>");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
+    QWeb.dev = dev;
+  });
+
+  test("conditional use of Portal", async () => {
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <span>1</span>
+          <Portal target="'#outside'" t-if="state.hasPortal">
+            <div>2</div>
+          </Portal>
+        </div>`;
+
+      state = useState({ hasPortal: false });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(outside.innerHTML).toBe("");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
+
+    parent.state.hasPortal = true;
+    await nextTick();
+    expect(outside.innerHTML).toBe("<div>2</div>");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
+
+    parent.state.hasPortal = false;
+    await nextTick();
+    expect(outside.innerHTML).toBe("");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
+
+    parent.state.hasPortal = true;
+    await nextTick();
+    expect(outside.innerHTML).toBe("<div>2</div>");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
+  });
+
+  test("conditional use of Portal (with sub Component)", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`<div><t t-esc="props.val"/></div>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <span>1</span>
+          <Portal t-if="state.hasPortal" target="'#outside'">
+            <Child val="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ hasPortal: false, val: 1 });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(outside.innerHTML).toBe("");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
+
+    parent.state.hasPortal = true;
+    await nextTick();
+    expect(outside.innerHTML).toBe("<div>1</div>");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
+
+    parent.state.hasPortal = false;
+    await nextTick();
+    expect(outside.innerHTML).toBe("");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
+
+    parent.state.val = 2;
+    await nextTick();
+    expect(outside.innerHTML).toBe("");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
+
+    parent.state.hasPortal = true;
+    await nextTick();
+    expect(outside.innerHTML).toBe("<div>2</div>");
+    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
+  });
+
+  test("with target in template (before portal)", async () => {
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <div id="local-target"></div>
+          <span>1</span>
+          <Portal target="'#local-target'">
+            <p>2</p>
+          </Portal>
+        </div>`;
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(parent.el!.innerHTML).toBe(
+      '<div id="local-target"><p>2</p></div><span>1</span><portal></portal>'
+    );
+  });
+
+  test("with target in template (after portal)", async () => {
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <span>1</span>
+          <Portal target="'#local-target'">
+            <p>2</p>
+          </Portal>
+          <div id="local-target"></div>
+        </div>`;
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(parent.el!.innerHTML).toBe(
+      '<span>1</span><portal></portal><div id="local-target"><p>2</p></div>'
+    );
+  });
+
+  test("portal with target not in dom", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#does-not-exist'">
+            <div>2</div>
+          </Portal>
+        </div>`;
+    }
+
+    const parent = new Parent();
+    let error;
+    try {
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+
+    expect(error).toBeDefined();
+    expect(error.message).toBe('Could not find any match for "#does-not-exist"');
+    expect(console.error).toBeCalledTimes(0);
+    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
+    console.error = consoleError;
+  });
+
+  test("portal with child and props", async () => {
+    const steps: string[] = [];
+    class Child extends Component<any, any> {
+      static template = xml`<span><t t-esc="props.val"/></span>`;
+      mounted() {
+        steps.push("mounted");
+        expect(outside.innerHTML).toBe("<span>1</span>");
+      }
+      patched() {
+        steps.push("patched");
+        expect(outside.innerHTML).toBe("<span>2</span>");
+      }
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <Child val="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ val: 1 });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(outside.innerHTML).toBe("<span>1</span>");
+    expect(parent.el!.innerHTML).toBe("<portal></portal>");
+
+    parent.state.val = 2;
+    await nextTick();
+    expect(outside.innerHTML).toBe("<span>2</span>");
+    expect(parent.el!.innerHTML).toBe("<portal></portal>");
+    expect(steps).toEqual(["mounted", "patched"]);
+  });
+
+  test("portal with only text as content", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <t t-esc="'only text'"/>
+          </Portal>
+        </div>`;
+    }
+
+    const parent = new Parent();
+    let error;
+    try {
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
+    expect(console.error).toBeCalledTimes(0);
+    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
+    console.error = consoleError;
+  });
+
+  test("portal with no content", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <t t-if="false" t-esc="'ABC'"/>
+          </Portal>
+        </div>`;
+    }
+
+    const parent = new Parent();
+    let error;
+    try {
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
+    expect(console.error).toBeCalledTimes(0);
+    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
+    console.error = consoleError;
+  });
+
+  test("portal with many children", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <div>1</div>
+            <p>2</p>
+          </Portal>
+        </div>`;
+    }
+    const parent = new Parent();
+    let error;
+    try {
+      await parent.mount(fixture);
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Portal must have exactly one non-text child (has 2)");
+    expect(console.error).toBeCalledTimes(0);
+    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
+    console.error = consoleError;
+  });
+
+  test("portal with dynamic body", async () => {
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <span t-if="state.val" t-esc="state.val"/>
+            <div t-else=""/>
+          </Portal>
+        </div>`;
+      state = useState({ val: "ab" });
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    expect(outside.innerHTML).toBe(`<span>ab</span>`);
+
+    parent.state.val = "";
+    await nextTick();
+    expect(outside.innerHTML).toBe(`<div></div>`);
+  });
+
+  test("portal could have dynamically no content", async () => {
+    const consoleError = console.error;
+    console.error = jest.fn(() => {});
+
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <span t-if="state.val" t-esc="state.val"/>
+          </Portal>
+        </div>`;
+      state = { val: "ab" };
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    expect(outside.innerHTML).toBe(`<span>ab</span>`);
+
+    let error;
+    try {
+      parent.state.val = "";
+      await parent.render();
+    } catch (e) {
+      error = e;
+    }
+    expect(outside.innerHTML).toBe(``);
+
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
+
+    expect(console.error).toBeCalledTimes(0);
+    console.error = consoleError;
+  });
+
+  test("lifecycle hooks of portal sub component are properly called", async () => {
+    const steps: any[] = [];
+
+    class Child extends Component<any, any> {
+      static template = xml`<span t-esc="props.val"/>`;
+      mounted() {
+        steps.push("child:mounted");
+      }
+      willPatch() {
+        steps.push("child:willPatch");
+      }
+      patched() {
+        steps.push("child:patched");
+      }
+      willUnmount() {
+        steps.push("child:willUnmount");
+      }
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <Portal t-if="state.hasChild" target="'#outside'">
+            <Child val="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ hasChild: false, val: 1 });
+      mounted() {
+        steps.push("parent:mounted");
+      }
+      willPatch() {
+        steps.push("parent:willPatch");
+      }
+      patched() {
+        steps.push("parent:patched");
+      }
+      willUnmount() {
+        steps.push("parent:willUnmount");
+      }
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+    expect(steps).toEqual(["parent:mounted"]);
+
+    parent.state.hasChild = true;
+    await nextTick();
+    expect(steps).toEqual([
+      "parent:mounted",
+      "parent:willPatch",
+      "child:mounted",
+      "parent:patched"
+    ]);
+
+    parent.state.val = 2;
+    await nextTick();
+    expect(steps).toEqual([
+      "parent:mounted",
+      "parent:willPatch",
+      "child:mounted",
+      "parent:patched",
+      "parent:willPatch",
+      "child:willPatch",
+      "child:patched",
+      "parent:patched"
+    ]);
+
+    parent.state.hasChild = false;
+    await nextTick();
+    expect(steps).toEqual([
+      "parent:mounted",
+      "parent:willPatch",
+      "child:mounted",
+      "parent:patched",
+      "parent:willPatch",
+      "child:willPatch",
+      "child:patched",
+      "parent:patched",
+      "parent:willPatch",
+      "child:willUnmount",
+      "parent:patched"
+    ]);
+  });
+
+  test("portal destroys on crash", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`<span t-esc="props.error and this.will.crash" />`;
+      state = {};
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'" >
+            <Child error="state.error"/>
+          </Portal>
+        </div>`;
+      state = { error: false };
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    parent.state.error = true;
+
+    let error;
+    try {
+      await parent.render();
+    } catch (e) {
+      error = e;
+    }
+    expect(error).toBeDefined();
+    expect(error.message).toBe("Cannot read property 'crash' of undefined");
+  });
+});
+
+describe("Portal: Events handling", () => {
+  test("events triggered on movable pure node are handled", async () => {
+    class Parent extends Component<any, any> {
+      static components = { Portal };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <span id="trigger-me" t-on-custom="_onCustom" t-esc="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ val: "ab" });
+
+      _onCustom() {
+        this.state.val = "triggered";
+      }
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    expect(outside.innerHTML).toBe(`<span id="trigger-me">ab</span>`);
+    outside.querySelector("#trigger-me")!.dispatchEvent(new Event("custom"));
+    await nextTick();
+    expect(outside.innerHTML).toBe(`<span id="trigger-me">triggered</span>`);
+  });
+
+  test("events triggered on movable owl components are redirected", async () => {
+    let childInst: Component<any, any> | null = null;
+    class Child extends Component<any, any> {
+      static template = xml`
+         <span t-on-custom="_onCustom" t-esc="props.val"/>`;
+
+      constructor(parent, props) {
+        super(parent, props);
+        childInst = this;
+      }
+
+      _onCustom() {
+        this.trigger("custom-portal");
+      }
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div t-on-custom-portal="_onCustomPortal">
+          <Portal target="'#outside'">
+            <Child val="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ val: "ab" });
+
+      _onCustomPortal() {
+        this.state.val = "triggered";
+      }
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    expect(outside.innerHTML).toBe(`<span>ab</span>`);
+    childInst!.trigger("custom");
+    await nextTick();
+    expect(outside.innerHTML).toBe(`<span>triggered</span>`);
+  });
+
+  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> {
+      static template = xml`
+         <span t-on-custom="_onCustom"/>`;
+
+      constructor(parent, props) {
+        super(parent, props);
+        childInst = this;
+      }
+
+      _onCustom() {
+        this.trigger("custom-portal");
+      }
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div t-on-custom="_handled" t-on-custom-portal="_handled">
+          <Portal target="'#outside'">
+            <div>
+              <Child/>
+            </div>
+          </Portal>
+        </div>`;
+
+      _handled(ev) {
+        steps.push(ev.type);
+      }
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    childInst!.trigger("custom");
+    await nextTick();
+
+    // This is expected because trigger is synchronous
+    expect(steps).toMatchObject(["custom-portal", "custom"]);
+  });
+
+  test("Dom events are not mapped", async () => {
+    let childInst: Component<any, any> | null = null;
+    const steps: string[] = [];
+    class Child extends Component<any, any> {
+      static template = xml`
+        <button>child</button>`;
+
+      constructor(parent, props) {
+        super(parent, props);
+        childInst = this;
+      }
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div t-on-click="_handled">
+          <Portal target="'#outside'">
+            <Child />
+          </Portal>
+        </div>`;
+
+      _handled(ev) {
+        steps.push(ev.type as string);
+      }
+    }
+    const bodyListener = ev => {
+      steps.push(`body: ${ev.type}`);
+    };
+    document.body.addEventListener("click", bodyListener);
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+    childInst!.el!.click();
+
+    expect(steps).toEqual(["body: click"]);
+    document.body.removeEventListener("click", bodyListener);
+  });
+
+  test("Nested portals event propagation", async () => {
+    const outside2 = document.createElement("div");
+    outside2.setAttribute("id", "outside2");
+    fixture.appendChild(outside2);
+
+    const steps: Array<string> = [];
+    let childInst: Component<any, any> | null = null;
+    class Child2 extends Component<any, any> {
+      static template = xml`<div>child2</div>`;
+      constructor(parent, props) {
+        super(parent, props);
+        childInst = this;
+      }
+    }
+    class Child extends Component<any, any> {
+      static components = { Portal, Child2 };
+      static template = xml`
+        <Portal target="'#outside2'">
+          <Child2 />
+        </Portal>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div t-on-custom='_handled'>
+          <Portal target="'#outside'">
+            <Child/>
+          </Portal>
+        </div>`;
+
+      _handled(ev) {
+        steps.push(`${ev.type} from ${ev.originalComponent.constructor.name}`);
+      }
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    childInst!.trigger("custom");
+    expect(steps).toEqual(["custom from Child2"]);
+  });
+
+  test("portal's parent's env is not polluted", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`
+        <button>child</button>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <Child />
+          </Portal>
+        </div>`;
+    }
+    const parent = new Parent();
+    const parentEnv = Object.assign({}, parent.env);
+    await parent.mount(fixture);
+    expect(parentEnv).toStrictEqual(parent.env);
+  });
+
+  test("Portal composed with t-slot", async () => {
+    const steps: Array<string> = [];
+    let childInst: Component<any, any> | null = null;
+    class Child2 extends Component<any, any> {
+      static template = xml`<div>child2</div>`;
+      constructor(parent, props) {
+        super(parent, props);
+        childInst = this;
+      }
+    }
+    class Child extends Component<any, any> {
+      static components = { Portal, Child2 };
+      static template = xml`
+        <Portal target="'#outside'">
+          <t t-slot="default"/>
+        </Portal>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Child, Child2 };
+      static template = xml`
+        <div t-on-custom='_handled'>
+          <Child>
+            <Child2/>
+          </Child>
+        </div>`;
+
+      _handled(ev) {
+        steps.push(ev.type as string);
+      }
+    }
+
+    const parent = new Parent();
+    await parent.mount(fixture);
+
+    childInst!.trigger("custom");
+    expect(steps).toEqual(["custom"]);
+  });
+});
+
+describe("Portal: UI/UX", () => {
+  test("focus is kept across re-renders", async () => {
+    class Child extends Component<any, any> {
+      static template = xml`
+        <input id="target-me" t-att-placeholder="props.val"/>`;
+    }
+    class Parent extends Component<any, any> {
+      static components = { Portal, Child };
+      static template = xml`
+        <div>
+          <Portal target="'#outside'">
+            <Child val="state.val"/>
+          </Portal>
+        </div>`;
+      state = useState({ val: "ab" });
+    }
+    const parent = new Parent();
+    await parent.mount(fixture);
+    const input = document.querySelector("#target-me");
+    expect(input!.nodeName).toBe("INPUT");
+    expect((input as HTMLInputElement).placeholder).toBe("ab");
+
+    (input as HTMLInputElement).focus();
+    expect(document.activeElement === input).toBeTruthy();
+
+    parent.state.val = "bc";
+    await nextTick();
+    const inputReRendered = document.querySelector("#target-me");
+    expect(inputReRendered!.nodeName).toBe("INPUT");
+    expect((inputReRendered as HTMLInputElement).placeholder).toBe("bc");
+    expect(document.activeElement === inputReRendered).toBeTruthy();
+  });
+});

tests/router/__snapshots__/link.test.ts.snap

@@ -6,16 +6,16 @@ exports[`Link component can render simple cases 1`] = `
     let utils = this.constructor.utils;
     let owner = context;
     var h = this.h;
-    let _6 = utils.toObj({'router-link-active':context['isActive']});
+    let _5 = utils.toObj({'router-link-active':context['isActive']});
-    var _7 = context['href'];
+    var _6 = context['href'];
-    let c8 = [], p8 = {key:8,attrs:{href: _7},class:_6,on:{}};
+    let c7 = [], p7 = {key:7,attrs:{href: _6},class:_5,on:{}};
-    var vn8 = h('a', p8, c8);
+    var vn7 = h('a', p7, c7);
-    extra.handlers['click' + 8] = extra.handlers['click' + 8] || function (e) {const fn = context['navigate'];if (fn) { fn.call(owner, e); } else { context.navigate; }};
+    extra.handlers['click' + 7] = extra.handlers['click' + 7] || function (e) {const fn = context['navigate'];if (fn) { fn.call(owner, e); } else { context.navigate; }};
-    p8.on['click'] = extra.handlers['click' + 8];
+    p7.on['click'] = extra.handlers['click' + 7];
-    const slot9 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    const slot8 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot9) {
+    if (slot8) {
-        slot9.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: c8, vars: extra.vars, parent: extra.parent || owner}));
+        slot8.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: c7, vars: extra.vars, parent: extra.parent || owner}));
     }
-    return vn8;
+    return vn7;
 }"
 `;

tests/router/__snapshots__/route_component.test.ts.snap

@@ -10,35 +10,33 @@ exports[`RouteComponent can render simple cases 1`] = `
     let result;
     var h = this.h;
     if (context['routeComponent']) {
-        const nodeKey6 = context['env'].router.currentRouteName;
+        const nodeKey5 = context['env'].router.currentRouteName;
         //COMPONENT
-        let k9 = \`__10__\` + nodeKey6;
+        let k7 = \`__8__\` + nodeKey5;
-        let w8 = k9 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k9]] : false;
+        let w6 = k7 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k7]] : false;
-        let vn11 = {};
+        let vn9 = {};
-        result = vn11;
+        result = vn9;
-        let props8 = Object.assign({}, context['env'].router.currentParams);
+        let props6 = Object.assign({}, context['env'].router.currentParams);
-        if (w8 && w8.__owl__.currentFiber && !w8.__owl__.vnode) {
+        if (w6 && w6.__owl__.currentFiber && !w6.__owl__.vnode) {
-            w8.destroy();
+            w6.destroy();
-            w8 = false;
+            w6 = false;
         }
-        if (w8) {
+        if (w6) {
-            w8.__updateProps(props8, extra.fiber, undefined, undefined);
+            w6.__updateProps(props6, extra.fiber, undefined, undefined);
-            let pvnode = w8.__owl__.pvnode;
+            let pvnode = w6.__owl__.pvnode;
-            utils.defineProxy(vn11, pvnode);
+            utils.defineProxy(vn9, pvnode);
         } else {
-            let componentKey8 = \`routeComponent\`;
+            let componentKey6 = \`routeComponent\`;
-            let W8 = context.constructor.components[componentKey8] || QWeb.components[componentKey8]|| context['routeComponent'];
+            let W6 = context.constructor.components[componentKey6] || QWeb.components[componentKey6]|| context['routeComponent'];
-            if (!W8) {throw new Error('Cannot find the definition of component \\"' + componentKey8 + '\\"')}
+            if (!W6) {throw new Error('Cannot find the definition of component \\"' + componentKey6 + '\\"')}
-            w8 = new W8(parent, props8);
+            w6 = new W6(parent, props6);
-            parent.__owl__.cmap[k9] = w8.__owl__.id;
+            parent.__owl__.cmap[k7] = w6.__owl__.id;
-            let def7 = w8.__prepare(extra.fiber, undefined, undefined);
+            let fiber = w6.__prepare(extra.fiber, undefined, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k9, hook: {remove() {},destroy(vn) {w8.destroy();}}});
+            let pvnode = h('dummy', {key: k7, hook: {remove() {},destroy(vn) {w6.destroy();}}});
-            const fiber = w8.__owl__.currentFiber;
+            utils.defineProxy(vn9, pvnode);
-            def7.then(function () { if (fiber.isCompleted) { return; } const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+            w6.__owl__.pvnode = pvnode;
-            utils.defineProxy(vn11, pvnode);
-            w8.__owl__.pvnode = pvnode;
         }
-        w8.__owl__.parentLastFiberId = extra.fiber.id;
+        w6.__owl__.parentLastFiberId = extra.fiber.id;
     }
     return result;
 }"

tests/tooling/debug_script_1.test.ts

@@ -0,0 +1,57 @@
+/**
+ * We can only make one test per file, since the debug tool modify in place
+ * the owl object in a way that is difficult to undo.
+ */
+
+import { debugOwl } from "../../tools/debug";
+import * as owl from "../../src/index";
+
+import { Component, Env } from "../../src/component/component";
+import { xml } from "../../src/tags";
+import { useState } from "../../src/hooks";
+import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
+
+let fixture: HTMLElement = makeTestFixture();
+let env: Env = makeTestEnv();
+Component.env = env;
+
+debugOwl(owl, {});
+
+test("can log full lifecycle", async () => {
+  const steps: string[] = [];
+  const log = console.log;
+  console.log = arg => steps.push(arg);
+
+  class Child extends Component<any, any> {
+    static template = xml`<div>child</div>`;
+  }
+
+  class Parent extends Component<any, any> {
+    static template = xml`<div><Child t-if="state.flag"/></div>`;
+    static components = { Child };
+    state = useState({ flag: false });
+  }
+
+  const parent = new Parent(null, {});
+  await parent.mount(fixture);
+
+  parent.state.flag = true;
+  await nextTick();
+
+  expect(steps).toEqual([
+    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
+    "[OWL_DEBUG] Parent<id=1> mount",
+    "[OWL_DEBUG] Parent<id=1> willStart",
+    "[OWL_DEBUG] Parent<id=1> rendering template",
+    "[OWL_DEBUG] Parent<id=1> mounted",
+    "[OWL_DEBUG] Parent<id=1> render",
+    "[OWL_DEBUG] Parent<id=1> rendering template",
+    "[OWL_DEBUG] Child<id=2> constructor, props={}",
+    "[OWL_DEBUG] Child<id=2> willStart",
+    "[OWL_DEBUG] Child<id=2> rendering template",
+    "[OWL_DEBUG] Parent<id=1> willPatch",
+    "[OWL_DEBUG] Child<id=2> mounted",
+    "[OWL_DEBUG] Parent<id=1> patched"
+  ]);
+  console.log = log;
+});

tests/tooling/debug_script_2.test.ts

@@ -0,0 +1,50 @@
+/**
+ * We can only make one test per file, since the debug tool modify in place
+ * the owl object in a way that is difficult to undo.
+ */
+
+import { debugOwl } from "../../tools/debug";
+import * as owl from "../../src/index";
+
+import { Component, Env } from "../../src/component/component";
+import { xml } from "../../src/tags";
+import { makeTestFixture, makeTestEnv } from "../helpers";
+
+let fixture: HTMLElement = makeTestFixture();
+let env: Env = makeTestEnv();
+Component.env = env;
+
+debugOwl(owl, { logScheduler: true });
+
+test("can log scheduler start and stop", async () => {
+  const steps: string[] = [];
+  const log = console.log;
+  console.log = arg => steps.push(arg);
+
+  class Child extends Component<any, any> {
+    static template = xml`<div>child</div>`;
+  }
+
+  class Parent extends Component<any, any> {
+    static template = xml`<div><Child /></div>`;
+    static components = { Child };
+  }
+
+  const parent = new Parent(null, {});
+  await parent.mount(fixture);
+
+  expect(steps).toEqual([
+    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
+    "[OWL_DEBUG] Parent<id=1> mount",
+    "[OWL_DEBUG] Parent<id=1> willStart",
+    "[OWL_DEBUG] scheduler: start running tasks queue",
+    "[OWL_DEBUG] Parent<id=1> rendering template",
+    "[OWL_DEBUG] Child<id=2> constructor, props={}",
+    "[OWL_DEBUG] Child<id=2> willStart",
+    "[OWL_DEBUG] Child<id=2> rendering template",
+    "[OWL_DEBUG] Child<id=2> mounted",
+    "[OWL_DEBUG] Parent<id=1> mounted",
+    "[OWL_DEBUG] scheduler: stop running tasks queue"
+  ]);
+  console.log = log;
+});

tests/tooling/doc_link_checker.test.ts

@@ -85,7 +85,7 @@ function getFiles(path: string[] = []): FileData[] {
   return Array.prototype.concat(...files);
 }
 
-const LOCAL_FILES = ["LICENSE"];
+const LOCAL_FILES = ["LICENSE", "tools/debug.js"];
 export function isLinkValid(link: MarkDownLink, current: FileData, files: FileData[]): boolean {
   if (link.link.startsWith("http")) {
     // no check on external links

tools/debug.js

@@ -0,0 +1,139 @@
+/**
+ * Debug Script
+ *
+ * This code is intended to be evaluated in an environment where owl is available,
+ * to log lot of helpful information on how Owl components behave.
+ */
+
+ function debugOwl(owl, options) {
+  let prefix = "[OWL_DEBUG]";
+  let current;
+  Object.defineProperty(owl.Component, "current", {
+    get() {
+      return current;
+    },
+    set(comp) {
+      current = comp;
+      const name = comp.constructor.name;
+      if (options.componentBlackList && options.componentBlackList.test(name)) {
+        return;
+      }
+      if (options.componentWhiteList && !options.componentWhiteList.test(name)) {
+        return;
+      }
+      let __owl__;
+      Object.defineProperty(current, "__owl__", {
+        get() {
+          return __owl__;
+        },
+        set(val) {
+          __owl__ = val;
+          debugComponent(comp, name, __owl__.id);
+        }
+      });
+    }
+  });
+
+  function toStr(obj) {
+    let str = JSON.stringify(obj || {});
+    if (str.length > 200) {
+      str = str.slice(0, 200) + "...";
+    }
+    return str;
+  }
+
+  function debugComponent(component, name, id) {
+    let fullName = `${name}<id=${id}>`;
+    let shouldDebug = method => {
+      if (options.methodBlackList && options.methodBlackList.includes(method)) {
+        return false;
+      }
+      if (options.methodWhiteList && !options.methodWhiteList.includes(method)) {
+        return false;
+      }
+      return true;
+    };
+    if (shouldDebug("constructor")) {
+      console.log(`${prefix} ${fullName} constructor, props=${toStr(component.props)}`);
+    }
+    if (shouldDebug("willStart")) {
+      owl.hooks.onWillStart(() => {
+        console.log(`${prefix} ${fullName} willStart`);
+      });
+    }
+    if (shouldDebug("mounted")) {
+      owl.hooks.onMounted(() => {
+        console.log(`${prefix} ${fullName} mounted`);
+      });
+    }
+    if (shouldDebug("willUpdateProps")) {
+      owl.hooks.onWillUpdateProps(nextProps => {
+        console.log(`${prefix} ${fullName} willUpdateProps, nextprops=${toStr(nextProps)}`);
+      });
+    }
+    if (shouldDebug("willPatch")) {
+      owl.hooks.onWillPatch(() => {
+        console.log(`${prefix} ${fullName} willPatch`);
+      });
+    }
+    if (shouldDebug("patched")) {
+      owl.hooks.onPatched(() => {
+        console.log(`${prefix} ${fullName} patched`);
+      });
+    }
+    if (shouldDebug("willUnmount")) {
+      owl.hooks.onWillUnmount(() => {
+        console.log(`${prefix} ${fullName} willUnmount`);
+      });
+    }
+    const __render = component.__render.bind(component);
+    component.__render = function(...args) {
+      console.log(`${prefix} ${fullName} rendering template`);
+      __render(...args);
+    };
+    const render = component.render.bind(component);
+    component.render = function(...args) {
+      console.log(`${prefix} ${fullName} render`);
+      return render(...args);
+    };
+    const mount = component.mount.bind(component);
+    component.mount = function(...args) {
+      console.log(`${prefix} ${fullName} mount`);
+      return mount(...args);
+    };
+  }
+
+  if (options.logScheduler) {
+    let start = owl.Component.scheduler.start;
+    let stop = owl.Component.scheduler.stop;
+    owl.Component.scheduler.start = function () {
+      console.log(`${prefix} scheduler: start running tasks queue`);
+      start.call(this);
+    };
+    owl.Component.scheduler.stop = function () {
+      console.log(`${prefix} scheduler: stop running tasks queue`);
+      stop.call(this);
+    };
+  }
+  if (options.logStore) {
+    let dispatch = owl.Store.prototype.dispatch;
+    owl.Store.prototype.dispatch = function(action, ...payload) {
+      console.log(`${prefix} store: action '${action}' dispatched. Payload: '${toStr(payload)}'`);
+      return dispatch.call(this, action, ...payload);
+    };
+  }
+}
+
+
+// This debug function can then be used like this:
+//
+// debugOwl(owl, {
+//   componentBlackList: /App/,  // regexp
+//   componentWhiteList: /SomeComponent/, // regexp
+//   methodBlackList: ["mounted"], // list of method names
+//   methodWhiteList: ["willStart"], // list of method names
+//   logScheduler: true, // display/mute scheduler logs
+//   logStore: true // display/mute store logs
+// });
+
+module.exports.debugOwl = debugOwl;

tools/playground/samples.js

@@ -1444,6 +1444,111 @@ const FORM_XML = `<templates>
 </templates>
 `;
 
+const PORTAL_COMPONENTS = `
+// This shows the expected use case of Portal
+// which is to implement something similar
+// to bootstrap modal
+const { Component, useState } = owl;
+const { Portal } = owl.misc;
+
+class Modal extends Component {}
+Modal.components = { Portal };
+
+class Dialog extends Component {}
+Dialog.components = { Modal };
+
+class Interstellar extends Component {}
+
+// Main root component
+class App extends Component {
+    state = useState({
+        name: 'Portal used for Dialog (Modal)',
+        dialog: false,
+        text: 'Hello !',
+    });
+}
+App.components = { Dialog , Interstellar };
+
+// Application setup
+const app = new App();
+app.mount(document.body);
+`;
+
+const PORTAL_XML = `
+<templates>
+  <t t-name="Modal">
+    <Portal target="'body'">
+        <div class="owl-modal-supercontainer">
+          <div class="owl-modal-backdrop"></div>
+          <div class="owl-modal-container">
+            <t t-slot="default" />
+          </div>
+        </div>
+    </Portal>
+  </t>
+
+  <t t-name="Dialog">
+    <Modal>
+      <div class="owl-dialog-body">
+        <t t-slot="default" />
+      </div>
+    </Modal>
+  </t>
+
+  <div t-name="Interstellar" class="owl-interstellar">
+    <h4>This is a subComponent</h4>
+    <p>The events it triggers will go through the Portal and be teleported
+    on the other side of the wormhole it has created</p>
+    <button t-on-click="trigger('collapse-all')">Close the wormhole</button>
+  </div>
+
+  <div t-name="App" t-on-collapse-all="state.dialog=false">
+    <div t-esc="state.name"/>
+    <button t-on-click="state.dialog = true">Open Dialog</button>
+    <Dialog t-if="state.dialog">
+      <div t-esc="state.text"/>
+      <Interstellar />
+    </Dialog>
+  </div>
+</templates>
+`;
+
+const PORTAL_CSS = `
+.owl-modal-supercontainer {
+  position: static;
+}
+.owl-modal-backdrop {
+    position: fixed;
+    top: 0;
+    left:0;
+    background-color: #000000;
+    opacity: 0.5;
+    width: 100vw;
+    height: 100vh;
+    z-index: 1000;
+}
+.owl-modal-container {
+    opacity:1;
+    z-index: 1050;
+    position: fixed;
+    top: 0;
+    left:0;
+    width: 100%;
+    height: 100%;
+}
+.owl-dialog-body {
+    max-width: 500px;
+    margin: 0 auto;
+    position: relative;
+    text-align: center;
+    padding: 2rem;
+    background-color: #FFFFFF;
+    max-height: 100%;
+}
+.owl-interstellar {
+    border: groove;
+}`
+
 const WMS = `// This example is slightly more complex than usual. We demonstrate
 // here a way to manage sub windows in Owl, declaratively. This is still just a
 // demonstration. Managing windows can be as complex as we want.  For example,
@@ -1770,5 +1875,11 @@ export const SAMPLES = [
     code: ASYNC_COMPONENTS,
     xml: ASYNC_COMPONENTS_XML,
     css: ASYNC_COMPONENTS_CSS
-  }
+  },
+  {
+    description: "Portal (Dialog)",
+    code: PORTAL_COMPONENTS,
+    xml: PORTAL_XML,
+    css: PORTAL_CSS,
+  },
 ];