| <!doctype html> |
| <meta charset="utf-8"> |
| <title>Container Queries - Style Change Event for transitions</title> |
| <link rel="help" href="https://drafts.csswg.org/css-transitions/#starting"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| .container { contain: size layout } |
| #outer { |
| width: 100px; |
| color: green; |
| } |
| @container (min-width: 200px) { |
| #inner { color: red } |
| } |
| @container (min-width: 400px) { |
| #target { |
| color: green; |
| transition: color 1s step-start; |
| } |
| } |
| </style> |
| <div id="outer" class="container"> |
| <div id="inner" class="container"> |
| <div id="target">Green</div> |
| </div> |
| </div> |
| </div> |
| <script> |
| const t = async_test(""); |
| const event_handler = t.step_func_done((e) => { |
| assert_unreached("Transition event incorrectly triggered: " + e.type); |
| }); |
| for (let event_name of ["transitionrun", |
| "transitionstart", |
| "transitionend", |
| "transitioncancel"]) { |
| target.addEventListener(event_name, event_handler); |
| } |
| |
| outer.offsetTop; |
| // #target is green. Making the #outer container 200px will turn #inner and |
| // #target red through inheritance. |
| outer.style.width = "200px"; |
| // Making #inner 400px will make #target green. |
| inner.style.width = "400px"; |
| // Both changes above should happen in one style change event and should not |
| // trigger any transition events. Run two rAFs to make sure any events have |
| // time to trigger. |
| requestAnimationFrame(() => requestAnimationFrame(t.step_func_done(() => { |
| assert_equals(getComputedStyle(inner).color, "rgb(255, 0, 0)", |
| "@container queries supported"); |
| }))); |
| </script> |
