tor-browser

The Tor Browser
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bug1287715-littlealchemy2.com-fix-audio-race-condition.js (1826B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 "use strict";
      6 
      7 /**
      8 * Bugs 1287715 - Audio intermittently does not work.
      9 *
     10 * The site relies on unspecified behavior in Chromium and WebKit where
     11 * they will defer firing loadedmetadata events until after a listener
     12 * for the event is attached. We can mimic that behavior here.
     13 */
     14 
     15 /* globals exportFunction */
     16 
     17 console.info(
     18  "loadedmetadata event is being deferred until GAME_READY. See https://bugzilla.mozilla.org/show_bug.cgi?id=1287715 for details."
     19 );
     20 
     21 let loadedmetadataEvent;
     22 let loadedmetadataListener;
     23 
     24 const { prototype } = window.wrappedJSObject.EventTarget;
     25 const { addEventListener, dispatchEvent } = prototype;
     26 
     27 Object.defineProperty(prototype, "addEventListener", {
     28  value: exportFunction(function (type, listener, cfg) {
     29    if (type?.toLowerCase() === "loadedmetadata") {
     30      loadedmetadataListener = listener;
     31      return addEventListener.call(
     32        this,
     33        type,
     34        exportFunction(e => {
     35          loadedmetadataEvent = e;
     36        }, window),
     37        cfg
     38      );
     39    }
     40    return addEventListener.call(this, type, listener, cfg);
     41  }, window),
     42 });
     43 
     44 Object.defineProperty(prototype, "dispatchEvent", {
     45  value: exportFunction(function (e) {
     46    if (
     47      e?.type === "GAME_READY" &&
     48      loadedmetadataEvent &&
     49      loadedmetadataListener
     50    ) {
     51      try {
     52        (loadedmetadataListener?.handleEvent ?? loadedmetadataListener)(
     53          loadedmetadataEvent
     54        );
     55      } catch (_) {
     56        console.trace(_);
     57      }
     58      loadedmetadataListener = undefined;
     59      loadedmetadataEvent = undefined;
     60    }
     61    return dispatchEvent.call(this, e);
     62  }, window),
     63 });