mozilla-central: testing/web-platform/tests/css/css-view-transitions/start-view-transtion-skips-active.html@1d422913e1cb1658224a2d269f8e4c9e80032d29

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>startViewTranstion cancels active transition</title>
  <link rel="help" href="https://www.w3.org/TR/css-view-transitions-1/">
</head>

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
  :root {
    view-transition-name: none;
  }
  #target {
    width: 100px;
    height: 100px;
    background: blue;
    contain: paint;
    view-transition-name: target;
  }
  #target.update-1 {
    height: 150px;
  }
  #target.update-2 {
    height: 200px;
  }
</style>

<body>
  <div id="target"></div>
</body>
<script>
  promise_test(async t => {
    let rejected_promise_tally = 0;
    const target = document.getElementById("target");
    assert_implements(document.startViewTransition,
                      "Missing document.startViewTransition");

    const verifyAbortedTransition = (promise) => {
      return promise.then(
        () => { assert_not_reached('transition aborted') },
        (reason) => {
          assert_true(reason instanceof DOMException);
          assert_equals(reason.code, DOMException.ABORT_ERR);
          rejected_promise_tally++;
        });
    };

    const vt1 = document.startViewTransition(() => {
      target.className = 'update-1';
    });
    const vt2 = document.startViewTransition(() => {
      assert_equals(target.className, 'update-1');
      target.className = 'update-2';
    });
    const vt3 = document.startViewTransition(() => {
      assert_equals(target.className, 'update-2');
    });

    await verifyAbortedTransition(vt1.ready);
    await verifyAbortedTransition(vt2.ready);
    await vt3.ready;

    assert_equals(rejected_promise_tally, 2,
                  'first 2 transitions are skipped');
    const sizeTransformAnimations = document.getAnimations().filter(a => {
      return 'height' in a.effect.getKeyframes()[0];
    });
    assert_equals(sizeTransformAnimations.length, 1);
    const startingHeight =
        sizeTransformAnimations[0].effect.getKeyframes()[0].height;

    assert_equals(startingHeight, '200px',
                  'Height change applied before capture');

  }, 'Synchronously starting a view transition skips the previously active ' +
     ' transition.');

</script>
</html>

author	Emilio Cobos Álvarez <emilio@crisal.io>
	Thu, 10 Jul 2025 09:08:54 +0000 (5 hours ago)
changeset 795952	1d422913e1cb1658224a2d269f8e4c9e80032d29
parent 778568	8c72e6d21ccaf06091f7ab5aa8d946f19a79b7cf
permissions	-rw-r--r--