test_finalizationRegistry_incumbent.html

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<html>

  <head>

    <meta charset="utf-8">

    <title>Test FinalizationRegistry tracks its incumbent global</title>

    <script src="/tests/SimpleTest/SimpleTest.js"></script>

    <script type="application/javascript">

      let resolvePromise, rejectPromise;

      async function runTest(global, callback) {

        let fr = new global.FinalizationRegistry(callback);

        fr.register({}, undefined);

        SpecialPowers.DOMWindowUtils.garbageCollect();

        let promise = new Promise((resolve, reject) => {

          resolvePromise = resolve;

          rejectPromise = reject;

});

        return promise;

      function receiveMessage(event) {

        resolvePromise(event.source.sourceName);

      async function go() {

        // This test uses FinalizationRegistry to trigger a callback and reports

        // the incumbent global in the callback using postMessage. In all cases

        // the author function that scheduled the callback is runTest(), so the

        // incumbent global should be the main window.

        SimpleTest.waitForExplicitFinish();

        window.sourceName = "main";

        window.addEventListener("message", receiveMessage, false);

        let other = window.frames[0];

        other.sourceName = "other";

        other.addEventListener("message", receiveMessage, false);

        is(await runTest(window, v => window.postMessage(v)), "main");

        is(await runTest(window, window.postMessage.bind(window)), "main");

        is(await runTest(other, v => other.postMessage(v)), "main");

        is(await runTest(other, other.postMessage.bind(other)), "main");

        is(await runTest(window, v => other.postMessage(v)), "main");

        is(await runTest(window, other.postMessage.bind(other)), "main");

        is(await runTest(other, v => window.postMessage(v)), "main");

        is(await runTest(other, window.postMessage.bind(window)), "main");

        SimpleTest.finish();

    </script>

  </head>

  <body onload="go()">

    <div style="display: none">

      <!-- A subframe so we have another global to work with -->

      <iframe></iframe>

    </div>

  </body>

</html>