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