| <!DOCTYPE HTML> |
| <meta charset=utf-8> |
| <title>Layout Instability entries are not available via the performance timeline</title> |
| <body> |
| <style> |
| #myDiv { position: relative; width: 300px; height: 100px; } |
| </style> |
| <div id='myDiv'></div> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <!-- Delay onload by inserting a slow image.--> |
| <img src="resources/slow-image.py"> |
| <script> |
| async_test(function (t) { |
| if (!window.LayoutShift) |
| assert_unreached('LayoutShift entries are not supported'); |
| const startTime = performance.now(); |
| new PerformanceObserver(list => { |
| const endTime = performance.now(); |
| assert_equals(list.getEntries().length, 1); |
| const entry = list.getEntries()[0]; |
| assert_equals(entry.entryType, "layout-shift"); |
| assert_equals(entry.name, ""); |
| assert_greater_than_equal(entry.startTime, startTime) |
| assert_less_than_equal(entry.startTime, endTime) |
| assert_equals(entry.duration, 0.0); |
| const maxDimension = Math.max(document.documentElement.clientWidth, |
| document.documentElement.clientHeight); |
| // The layout shift value should be: |
| // 300 * (100 + 60) * (60 / maxDimension) / viewport size. |
| assert_equals(entry.value, 300 * (100 + 60) * (60 / maxDimension) / |
| (document.documentElement.clientWidth * document.documentElement.clientHeight)); |
| |
| // The entry should not be available via getEntries* methods. |
| assert_equals(performance.getEntriesByType('layout-shift').length, 0, 'getEntriesByType should have no layout-shift entries'); |
| assert_equals(performance.getEntriesByName('', 'layout-shift').length, 0, 'getEntriesByName should have no layout-shift entries'); |
| assert_equals(performance.getEntries().filter(e => e.entryType === 'layout-shift').length, 0, 'getEntries should have no layout-shift entries'); |
| t.done(); |
| }).observe({type: 'layout-shift'}); |
| // Modify the position of the div. |
| document.getElementById('myDiv').style = "top: 60px"; |
| }, 'Layout shift before onload is not buffered into the performance timeline.'); |
| </script> |
| |
| </body> |
