93 lines
3.4 KiB
HTML
93 lines
3.4 KiB
HTML
<!DOCTYPE HTML>
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<meta charset=utf-8>
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<title>Largest Contentful Paint: largest text is reported.</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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<style type="text/css">
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#text2 {
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position: absolute;
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width: auto;
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white-space: nowrap;
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}
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</style>
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<!-- These are some text and some tiny images. We care about the largest text. -->
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<img id='image1' />
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<div id='text1'></div>
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<div id='text2'></div>
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<img id='image2' />
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<script>
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const load_image = async (id, url) => {
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await new Promise(resolve => {
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const image = document.getElementById(id);
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image.addEventListener('load', resolve);
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image.src = url;
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});
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}
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const load_text = (id, text) => {
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let div = document.getElementById(id);
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div.innerHTML = text;
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}
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promise_test(async (t) => {
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assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
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let beforeRender = performance.now();
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// Load images and add texts.
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await load_image('image1', '/images/lcp-1x1.png');
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load_text('text1', 'This is some text.');
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load_text('text2', 'This is more text so it will be the Largest Contentful Paint!');
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await load_image('image2', '/images/lcp-2x2.png');
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await new Promise(resolve => {
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new PerformanceObserver(
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(entryList, observer) => {
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entryList.getEntries().forEach(entry => {
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// The tiny images or text1 could be reported as LCP if it is rendered before text2.
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if (entry.id !== 'text2')
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return;
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assert_equals(entry.entryType, 'largest-contentful-paint',
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'The entry entryType should be largest-contentful-paint.');
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assert_greater_than_equal(entry.renderTime, beforeRender,
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'The entry renderTime should be greater than or equal to the beforeRender.');
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assert_greater_than_equal(performance.now(), entry.renderTime,
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'The performance.now() timestamp should be greater than or equal to the entry renderTime.');
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assert_approx_equals(entry.startTime, entry.renderTime, 0.001,
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'The entry startTime should be equal to renderTime to the precision of 1 millisecond.');
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assert_equals(entry.duration, 0, 'The entry duration should be 0.');
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const div = document.getElementById('text2');
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// The div styling makes it approximate the text size.
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assert_greater_than_equal(entry.size, (div.clientHeight - 5) * (div.clientWidth - 5),
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'Reported LCP size should not be significantly smaller than the text2 div.');
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assert_less_than_equal(entry.size, (div.clientHeight + 1) * (div.clientWidth + 1),
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'Reported LCP size should not be larger than the text2 div.');
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assert_equals(entry.loadTime, 0, 'The entry loadTime should be 0.');
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assert_equals(entry.url, '', 'The entry url should be empty.');
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assert_equals(entry.element, div, 'The entry element should be test2 div.');
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observer.disconnect();
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resolve();
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})
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}).observe({ type: 'largest-contentful-paint', buffered: true });
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});
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}, 'Largest Contentful Paint: largest text is reported.');
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</script>
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</body>
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