37 lines
1 KiB
HTML
37 lines
1 KiB
HTML
<!DOCTYPE html>
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<title>Layout Instability: shift while scrolled</title>
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<link rel="help" href="https://wicg.github.io/layout-instability/" />
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<style>
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body { height: 2000px; margin: 0; }
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#shift { position: relative; width: 300px; height: 200px; background: blue; }
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</style>
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<div id="shift"></div>
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<script src="resources/util.js"></script>
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<script>
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promise_test(async () => {
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const watcher = new ScoreWatcher;
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// Wait for the initial render to complete.
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await waitForAnimationFrames(2);
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// Scroll down by 100px.
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document.scrollingElement.scrollTop = 100;
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assert_equals(watcher.score, 0);
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// Generate a layout shift.
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document.querySelector("#shift").style = "top: 60px";
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// Impact region: width * (height - scrollTop + moveDistance)
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const expectedScore = computeExpectedScore(
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300 * (200 - 100 + 60), 60);
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await watcher.promise;
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assert_equals(watcher.score, expectedScore);
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}, 'Layout shift with non-zero scroll offset.');
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</script>
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