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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /largest-contentful-paint/update-on-style-change.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<meta charset="utf-8">
<title>LargestContentfulPaint entries should NOT be emitted for updates to previous LargestContentfulPaint elements.</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
promise_test(async (t) => {
assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
let lcpEntries = [];
await new Promise(resolve => t.step_timeout(() => {
new PerformanceObserver(list => {
lcpEntries = lcpEntries.concat(list.getEntries())
if (lcpEntries.length > 1) {
assert_unreached("There shouldn't be more than 1 LCP entry for an element.");
}
if (lcpEntries) {
assert_equals(lcpEntries.length, 1, "There should be only 1 LCP entry for one element. ");
assert_equals(lcpEntries[0].id, "text", "The LCP should have id 'text'");
resolve();
}
}).observe({ type: 'largest-contentful-paint', buffered: true });
}, 200));
})
</script>
<div id="text">text</div>
<link rel="stylesheet" href="/resources/slow-style-change.py">
</body>