44 lines
1.5 KiB
HTML
44 lines
1.5 KiB
HTML
<!DOCTYPE html>
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<html>
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<meta name="viewport" content="width=device-width">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<link rel="author" title="Mozilla" href="https://mozilla.org">
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<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring/">
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<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1852818">
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<style>
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div {
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height: 100vh;
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}
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</style>
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<div></div>
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<div id="anchor" style="height: 10px; background-color: blue;"></div>
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<div></div>
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<script>
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promise_test(async t => {
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assert_equals(window.scrollY, 0);
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let anchorRect = anchor.getBoundingClientRect();
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// Scroll to the anchor node.
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window.scrollBy(0, anchorRect.y);
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assert_equals(window.scrollY, anchorRect.y);
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await new Promise(resolve => t.step_timeout(resolve, 0));
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// Expand the first element so that scroll anchoring happens.
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document.querySelectorAll("div")[0].style.height = "200vh";
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// Flush the change.
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document.querySelectorAll("div")[0].getBoundingClientRect();
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await new Promise(resolve => window.addEventListener("scroll", resolve));
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// Revert the height change in a scroll event handler.
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document.querySelectorAll("div")[0].style.height = "";
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await new Promise(resolve => requestAnimationFrame(resolve));
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await new Promise(resolve => requestAnimationFrame(resolve));
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assert_equals(window.scrollY, anchorRect.y);
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}, "Scroll anchoring properly works after scrollable range shrinkage");
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</script>
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</html>
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