display-none-prevents-starting-in-subtree.html

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This WPT test may be referenced by the following Test IDs:
- /css/css-animations/display-none-prevents-starting-in-subtree.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<link rel=author href="mailto:graouts@webkit.org">

<link rel=help href="https://drafts.csswg.org/css-animations/#animations">

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

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

<script src="/css/css-animations/support/testcommon.js"></script>

<style>

@keyframes margin {

    100% { margin-left: 200px }

#child {

  animation: margin 1s forwards;

</style>

<div id="container">

    <div>

        <div id="child"></div>

    </div>

</div>

<script>

test(() => {

  const container = document.getElementById("container");

  const animationCount = () => container.getAnimations({ subtree: true }).length;

  assert_equals(animationCount(), 1, `An animation is running on the child initially with "display: block" on the container.`);

  container.style.display = "none";

  assert_equals(animationCount(), 0, `Setting "display: none" on the container canceled the animation.`);

  container.style.marginLeft = "50px";

  container.firstElementChild.style.marginLeft = "100px";

  assert_equals(animationCount(), 0, `Manipulating styles on the container and a child element does not restart the animation.`);

}, 'Elements in a "display: none" tree cannot start CSS Animations.');

</script>