js/xpconnect/tests/mochitest/test_weakRefs.html

   1 <!DOCTYPE HTML>
   2 <html>
   3   <head>
   4     <meta charset="utf-8">
   5     <title>Test WeakRef works in the browser</title>
   6     <script src="/tests/SimpleTest/SimpleTest.js"></script>
   7     <script type="application/javascript">
   8       let wr1, wr2, wr3, wr4;
   9
  10       function go() {
  11         SimpleTest.waitForExplicitFinish();
  12
  13         // 1. WeakRef with JS target.
  14         wr1 = new WeakRef({});
  15
  16         // 2. WeakRef with DOM object target (without preserved wrapper).
  17         wr2 = new WeakRef(document.createElement("div"));
  18
  19         // 3. WeakRef with DOM object target (with preserved wrapper).
  20         let object = document.createElement("div");
  21         object.someProperty = true;
  22         wr3 = new WeakRef(object);
  23         object = null
  24
  25         // 4. WeakRef with reachable DOM object target without preserved wrapper.
  26         document.body.appendChild(document.createElement("div"));
  27         wr4 = new WeakRef(document.body.lastChild);
  28
  29         // WeakRef should keep the target in the current task.
  30         isnot(wr1.deref(), undefined, "deref() should return its target.");
  31         isnot(wr2.deref(), undefined, "deref() should return its target.");
  32         isnot(wr3.deref(), undefined, "deref() should return its target.");
  33         isnot(wr4.deref(), undefined, "deref() should return its target.");
  34
  35         // WeakRef should keep the target until the end of current task, which
  36         // includes promise microtasks.
  37         Promise.resolve().then(() => {
  38           isnot(wr1.deref(), undefined, "deref() should return its target.");
  39           isnot(wr2.deref(), undefined, "deref() should return its target.");
  40           isnot(wr3.deref(), undefined, "deref() should return its target.");
  41           isnot(wr4.deref(), undefined, "deref() should return its target.");
  42         });
  43
  44         // setTimeout will call its callback in a new task.
  45         setTimeout(task2, 0);
  46       }
  47
  48       function task2() {
  49         // Trigger a full GC/CC/GC cycle to collect WeakRef targets.
  50         SpecialPowers.DOMWindowUtils.garbageCollect();
  51         SpecialPowers.DOMWindowUtils.cycleCollect();
  52         SpecialPowers.DOMWindowUtils.garbageCollect();
  53
  54         is(wr1.deref(), undefined, "deref() should return undefined.");
  55         is(wr2.deref(), undefined, "deref() should return undefined.");
  56         is(wr3.deref(), undefined, "deref() should return undefined.");
  57         isnot(wr4.deref(), undefined, "deref() should return its target.");
  58
  59         // setTimeout will call its callback in a new task.
  60         setTimeout(task3, 0);
  61       }
  62
  63       function task3() {
  64         document.body.removeChild(document.body.lastChild);
  65
  66         SpecialPowers.DOMWindowUtils.garbageCollect();
  67         SpecialPowers.DOMWindowUtils.cycleCollect();
  68         SpecialPowers.DOMWindowUtils.garbageCollect();
  69
  70         is(wr1.deref(), undefined, "deref() should return undefined.");
  71         is(wr2.deref(), undefined, "deref() should return undefined.");
  72         is(wr3.deref(), undefined, "deref() should return undefined.");
  73         is(wr4.deref(), undefined, "deref() should return undefined.");
  74
  75         SimpleTest.finish();
  76       }
  77     </script>
  78   </head>
  79   <body onload="go()"></body>
  80 </html>