[FIX] update playground code to last version

playground/utils.js

@@ -0,0 +1,49 @@
+export function debounce(func, wait, immediate) {
+  let timeout;
+  return function () {
+    const context = this;
+    const args = arguments;
+    function later() {
+      timeout = null;
+      if (!immediate) {
+        func.apply(context, args);
+      }
+    }
+    const callNow = immediate && !timeout;
+    clearTimeout(timeout);
+    timeout = setTimeout(later, wait);
+    if (callNow) {
+      func.apply(context, args);
+    }
+  };
+}
+
+export function useBus(bus, evName, cb) {
+  bus.addEventListener(evName, cb);
+  owl.onWillUnmount(() => {
+    bus.removeEventListener(evName, cb);
+  });
+}
+
+const loadedScripts = {};
+
+export function loadJS(url) {
+  if (url in loadedScripts) {
+    return loadedScripts[url];
+  }
+  const promise = new Promise(function (resolve, reject) {
+    const script = document.createElement("script");
+    script.type = "text/javascript";
+    script.src = url;
+    script.onload = function () {
+      resolve();
+    };
+    script.onerror = function () {
+      reject(`Error loading file '${url}'`);
+    };
+    const head = document.head || document.getElementsByTagName("head")[0];
+    head.appendChild(script);
+  });
+  loadedScripts[url] = promise;
+  return promise;
+}