chromium/third_party/blink/web_tests/external/wpt/web-animations/interfaces/Animation/persist.html

<!doctype html>
<meta charset=utf-8>
<title>Animation.persist</title>
<link rel="help" href="https://drafts.csswg.org/web-animations/#dom-animation-persist">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../../testcommon.js"></script>
<body>
<div id="log"></div>
<script>
'use strict';

async_test(t => {
  const div = createDiv(t);

  const animA = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });
  const animB = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });

  animA.onremove = t.step_func_done(() => {
    assert_equals(animA.replaceState, 'removed');
    animA.persist();
    assert_equals(animA.replaceState, 'persisted');
  });
}, 'Allows an animation to be persisted after being removed');

promise_test(async t => {
  const div = createDiv(t);

  const animA = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });
  const animB = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });

  animA.persist();

  await animA.finished;

  assert_equals(animA.replaceState, 'persisted');
}, 'Allows an animation to be persisted before being removed');

</script>
</body>