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39 lines
1.7 KiB
HTML
39 lines
1.7 KiB
HTML
<!DOCTYPE HTML>
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<meta charset=utf-8>
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<title>Largest Contentful Paint: delayed appended image.</title>
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<body>
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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>
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async_test(function (t) {
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if (!window.LargestContentfulPaint) {
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assert_unreached("LargestContentfulPaint is not implemented");
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}
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let beforeLoad;
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const observer = new PerformanceObserver(
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t.step_func_done(entryList => {
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assert_equals(entryList.getEntries().length, 1);
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const entry = entryList.getEntries()[0];
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assert_equals(entry.entryType, 'largest-contentful-paint');
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assert_equals(entry.startTime, entry.renderTime, 'startTime should equal renderTime');
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assert_equals(entry.duration, 0);
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assert_equals(entry.url, window.location.origin + '/images/black-rectangle.png');
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assert_greater_than(entry.renderTime, entry.loadTime,
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'The image render time should occur after it is appended to the div.');
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assert_greater_than(entry.loadTime, beforeLoad,
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'The image load timestamp should occur after script starts running.');
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assert_less_than(entry.renderTime, performance.now(),
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'Image render time should be before the observer callback is executed.')
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})
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);
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observer.observe({type: 'largest-contentful-paint', buffered: true});
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const img = document.createElement('img');
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img.src = '/images/black-rectangle.png';
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t.step_timeout(() => {
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beforeLoad = performance.now();
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document.getElementById('image_div').appendChild(img);
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}, 200)
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}, 'Image loadTime occurs after appendChild is called.');
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</script>
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<div id='image_div'></div>
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</body>
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