| <!DOCTYPE HTML> |
| <meta charset=utf-8> |
| <title>Largest Contentful Paint: largest text is reported.</title> |
| <body> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style type="text/css"> |
| #text2 { |
| position: absolute; |
| width: auto; |
| white-space: nowrap; |
| } |
| </style> |
| <!-- There is some text and some tiny images. We care about the largest text. --> |
| <img src='/images/green-1x1.png'/> |
| <div id='text1'>This is some text.</div> |
| <div id='text2'>This is more text so it will be the Largest Contentful Paint!</div> |
| <img src='/images/green-2x2.png'/> |
| <script> |
| async_test(function (t) { |
| assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented"); |
| let beforeRender; |
| const observer = new PerformanceObserver( |
| t.step_func(entryList => { |
| entryList.getEntries().forEach(entry => { |
| // The tiny images or text1 could be reported as LCP if it is rendered before text2. |
| if (entry.id !== 'text2') |
| return; |
| |
| assert_equals(entry.entryType, 'largest-contentful-paint'); |
| assert_greater_than_equal(entry.renderTime, beforeRender); |
| assert_greater_than_equal(performance.now(), entry.renderTime); |
| assert_equals(entry.startTime, entry.renderTime, 'startTime should equal renderTime'); |
| assert_equals(entry.duration, 0); |
| const div = document.getElementById('text2'); |
| // The div styling makes it approximate the text size. |
| assert_greater_than_equal(entry.size, (div.clientHeight - 5) * (div.clientWidth - 5)); |
| assert_less_than_equal(entry.size, (div.clientHeight + 1) * (div.clientWidth + 1)); |
| assert_equals(entry.loadTime, 0); |
| assert_equals(entry.id, 'text2'); |
| assert_equals(entry.url, ''); |
| assert_equals(entry.element, div); |
| t.done(); |
| }) |
| }) |
| ); |
| observer.observe({type: 'largest-contentful-paint', buffered: true}); |
| beforeRender = performance.now(); |
| }, 'Largest Contentful Paint: largest text is reported.'); |
| </script> |
| </body> |
