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- This WPT test may be referenced by the following Test IDs:
- /css/css-conditional/container-queries/transition-style-change-event.html - WPT Dashboard Interop Dashboard
<!doctype html>
<meta charset="utf-8">
<title>Container Queries - Style Change Event for transitions</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/cq-testcommon.js"></script>
<style>
.container { container-type: size }
#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>
setup(() => assert_implements_size_container_queries());
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>