display-none-prevents-starting-in-subtree.html (1253B)
1 <!DOCTYPE html> 2 <link rel=author href="mailto:graouts@webkit.org"> 3 <link rel=help href="https://drafts.csswg.org/css-animations/#animations"> 4 <script src="/resources/testharness.js"></script> 5 <script src="/resources/testharnessreport.js"></script> 6 <script src="/css/css-animations/support/testcommon.js"></script> 7 <style> 8 @keyframes margin { 9 100% { margin-left: 200px } 10 } 11 12 #child { 13 animation: margin 1s forwards; 14 } 15 </style> 16 <div id="container"> 17 <div> 18 <div id="child"></div> 19 </div> 20 </div> 21 <script> 22 test(() => { 23 const container = document.getElementById("container"); 24 const animationCount = () => container.getAnimations({ subtree: true }).length; 25 26 assert_equals(animationCount(), 1, `An animation is running on the child initially with "display: block" on the container.`); 27 28 container.style.display = "none"; 29 assert_equals(animationCount(), 0, `Setting "display: none" on the container canceled the animation.`); 30 31 container.style.marginLeft = "50px"; 32 container.firstElementChild.style.marginLeft = "100px"; 33 assert_equals(animationCount(), 0, `Manipulating styles on the container and a child element does not restart the animation.`); 34 }, 'Elements in a "display: none" tree cannot start CSS Animations.'); 35 </script>