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Add tentative scroll-state(stuck) for snapshot timing after scroll #58739

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Merged
chromium-wpt-export-bot merged 1 commit into from
Mar 25, 2026
Merged

Add tentative scroll-state(stuck) for snapshot timing after scroll #58739

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104 changes: 104 additions & 0 deletions ...al/container-queries/scroll-state/scroll-state-stuck-snapshot-after-scroll.tentative.html
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Original file line number Diff line number Diff line change
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<!DOCTYPE html>
<title>@container: scroll-state(stuck) post-layout snapshot after scroll</title>
<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#stuck">
<link rel="help" href="https://github.com/whatwg/html/pull/11613/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
#scroller {
overflow-y: scroll;
height: 300px;
}
#filler {
height: 300px;
}
#stuck {
container-type: scroll-state;
position: sticky;
top: 0;
height: 100px;
background-color: teal;
}
#target {
--stuck: no;
@container scroll-state(stuck: top) {
--stuck: yes;
}
}
#resizeTrigger, #intersectionTrigger {
position: absolute;
left: 0;
top: 0;
width: 10px;
height: 10px;
}
#resizeTrigger.flip {
width: 20px;
height: 20px;
}
#intersectionTrigger.flip {
top: -1000px;
}
</style>
<div id="scroller">
<div id="stuck">
<span id="target"></span>
</div>
<div id="filler"></div>
</div>
<div id="intersectionTrigger"></div>
<div id="resizeTrigger"></div>
<script>
let resize_observer_callback = undefined;
function triggerResizeObserver(callback_function) {
resize_observer_callback = callback_function;
resizeTrigger.classList.toggle("flip");
}
(new ResizeObserver(entries => {
if (resize_observer_callback) {
resize_observer_callback();
resize_observer_callback = undefined;
}
})).observe(resizeTrigger);

let intersection_observer_callback = undefined;
function triggerIntersectionObserver(callback_function) {
intersection_observer_callback = callback_function;
intersectionTrigger.classList.toggle("flip");
}
(new IntersectionObserver(entries => {
if (intersection_observer_callback) {
intersection_observer_callback();
intersection_observer_callback = undefined;
}
})).observe(intersectionTrigger);

async_test((t) => {
requestAnimationFrame(() => {
requestAnimationFrame(() => {
triggerResizeObserver(() => {
t.step(() => {
assert_equals(getComputedStyle(target).getPropertyValue("--stuck"), "no",
"Not stuck after first frame");
// Change scroll position at intersection observer time to make sure
// the new scroll position is not taken into account for rendering
// in the current frame.
triggerIntersectionObserver(() => { scroller.scrollTop = 100; });
});
});
requestAnimationFrame(() => {
t.step(() => {
assert_equals(scroller.scrollTop, 100);
assert_equals(getComputedStyle(target).getPropertyValue("--stuck"), "no");
}, "scrollTop changed but snapshot is not updated before updating style and layout in the resizeObserver loop");
triggerResizeObserver(() => {
t.step(() => {
assert_equals(getComputedStyle(target).getPropertyValue("--stuck"), "yes");
t.done();
}, "At resizeObserver time, run snapshot post-layout state steps has been run and rendering was updated accordingly");
});
});
});
});
}, "Test that stuck state is updated in the resizeObserver loop");
</script>
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