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47 lines
2.1 KiB
HTML
47 lines
2.1 KiB
HTML
<!DOCTYPE HTML>
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<meta charset=utf-8>
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<title>Largest Contentful Paint: observe 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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const beforeRender = performance.now();
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const observer = new PerformanceObserver(
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t.step_func_done(function(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_greater_than_equal(entry.renderTime, beforeRender,
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'The rendering timestamp should occur after script starts running.');
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assert_greater_than_equal(performance.now(), entry.renderTime,
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'The rendering timestamp should occur before the entry is dispatched to the observer.');
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assert_equals(entry.startTime, 0);
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assert_equals(entry.duration, 0);
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// blue.png is 133 x 106.
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assert_equals(entry.size, 14098);
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assert_equals(entry.id, 'image_id');
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// 25 is the length of "largest-contentful-paint/".
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const index = window.location.href.lastIndexOf('/') - 25;
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const pathname = window.location.href.substring(0, index) + '/images/blue.png';
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assert_equals(entry.url, pathname);
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assert_greater_than(entry.loadTime, beforeRender,
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'The load timestamp should occur after script starts running.');
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assert_less_than(entry.loadTime, entry.renderTime,
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'The load timestamp should occur before the render timestamp.')
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assert_equals(entry.element, document.getElementById('image_id'));
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})
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);
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observer.observe({type: 'largest-contentful-paint', buffered: true});
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}, 'Same-origin image after a JS initiated scroll event is observable.');
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document.body.dispatchEvent(new Event('scroll'));
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const image = new Image();
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image.id = 'image_id';
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image.src = '/images/blue.png';
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document.body.appendChild(image);
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</script>
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</body>
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