| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 1 | <!DOCTYPE HTML> |
| 2 | <meta charset=utf-8> |
| 3 | <title>LargestContentfulPaint compared with FirstPaint and FirstContentfulPaint on single text page.</title> |
| 4 | <body> |
| 5 | <script src="/resources/testharness.js"></script> |
| 6 | <script src="/resources/testharnessreport.js"></script> |
| 7 | <script> |
| Sean Feng | a3cb53d | 2023-04-21 16:11:07 | [diff] [blame] | 8 | setup({"hide_test_state": true}); |
| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 9 | async_test(function (t) { |
| Stephen McGruer | b291cab | 2020-04-16 15:42:28 | [diff] [blame] | 10 | assert_implements(window.PerformancePaintTiming, "PerformancePaintTiming is not implemented"); |
| 11 | assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented"); |
| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 12 | let firstPaintTime = 0; |
| 13 | let firstContentfulPaintTime = 0; |
| 14 | let largestContentfulPaintTime = 0; |
| 15 | const observer = new PerformanceObserver( |
| 16 | t.step_func(function(entryList) { |
| Blink WPT Bot | ef41368 | 2024-12-10 01:11:21 | [diff] [blame] | 17 | entryList.getEntries().forEach(entry => { |
| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 18 | if (entry.name === 'first-paint') { |
| 19 | assert_equals(firstPaintTime, 0, 'Only one first-paint entry.'); |
| 20 | assert_equals(entry.entryType, 'paint'); |
| 21 | firstPaintTime = entry.startTime; |
| 22 | } else if (entry.name === 'first-contentful-paint') { |
| 23 | assert_equals(firstContentfulPaintTime, 0, 'Only one first-contentful-paint entry.'); |
| 24 | assert_equals(entry.entryType, 'paint'); |
| 25 | firstContentfulPaintTime = entry.startTime; |
| 26 | } else { |
| 27 | assert_equals(largestContentfulPaintTime, 0, 'Only one largest-contentful-paint entry.'); |
| 28 | assert_equals(entry.entryType, 'largest-contentful-paint'); |
| 29 | largestContentfulPaintTime = entry.renderTime; |
| 30 | } |
| Sean Feng | a3cb53d | 2023-04-21 16:11:07 | [diff] [blame] | 31 | // LCP fires necessarily after first-paint and first-contentful-paint. |
| 32 | if (largestContentfulPaintTime) { |
| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 33 | assert_equals(firstContentfulPaintTime, largestContentfulPaintTime, 'FCP should equal LCP.'); |
| Sean Feng | a3cb53d | 2023-04-21 16:11:07 | [diff] [blame] | 34 | // In PaintTiming spec, first-paint isn't a hard requirement, browsers can support |
| 35 | // first-contentful-paint only. |
| 36 | if (firstPaintTime) { |
| 37 | assert_less_than_equal(firstPaintTime, firstContentfulPaintTime, 'FP should be less than or equal to FCP.'); |
| 38 | } |
| Nicolás Peña Moreno | ef41eb1 | 2019-10-17 16:51:56 | [diff] [blame] | 39 | t.done(); |
| 40 | } |
| 41 | }); |
| 42 | }) |
| 43 | ); |
| 44 | observer.observe({type: 'largest-contentful-paint', buffered: true}); |
| 45 | observer.observe({type: 'paint', buffered: true}); |
| 46 | }, 'FCP and LCP are the same when there is a single text element in the page.'); |
| 47 | </script> |
| 48 | <p>Text</p> |
| 49 | </body> |
