| <!doctype html> |
| <meta charset=utf-8> |
| <title>Transitions start at the same time regardless of on-screen status</title> |
| <link rel="help" href="https://drafts.csswg.org/css-animations-2/"> |
| <link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1888748"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| .transition { |
| width: 100px; |
| height: 100px; |
| background-color: blue; |
| transition: translate 10000ms linear; |
| will-change: translate; |
| translate: 0; |
| } |
| .offscreen { |
| background-color: purple; |
| translate: -1000px; |
| } |
| </style> |
| <div class="transition"></div> |
| <div class="transition offscreen"></div> |
| <script> |
| 'use strict'; |
| |
| promise_test(async t => { |
| let [a, b] = document.querySelectorAll(".transition"); |
| |
| // Ensure a paint happens to make sure a transition gets triggered (otherwise |
| // getAnimations() would flush sync, and maybe not trigger a transition if |
| // it's the first style of the elements). |
| await new Promise(r => requestAnimationFrame(() => requestAnimationFrame(r))); |
| |
| // Trigger both transitions at the same time. |
| a.style.translate = b.style.translate = "100px"; |
| |
| let ta = a.getAnimations()[0]; |
| let tb = b.getAnimations()[0]; |
| |
| await Promise.all([ta.ready, tb.ready]); |
| assert_equals(ta.startTime, tb.startTime, "Both transitions should've started at the same time"); |
| }); |
| </script> |
