disconnect-image.html (1703B)
1 <!DOCTYPE HTML> 2 <meta charset=utf-8> 3 <title>Element Timing: element attribute returns null when element is disconnected</title> 4 <body> 5 <script src="/resources/testharness.js"></script> 6 <script src="/resources/testharnessreport.js"></script> 7 <script src="resources/element-timing-helpers.js"></script> 8 <script> 9 let beforeRender; 10 let img; 11 async_test(function (t) { 12 assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented"); 13 const observer = new PerformanceObserver( 14 t.step_func_done(function(entryList) { 15 assert_equals(entryList.getEntries().length, 1); 16 const entry = entryList.getEntries()[0]; 17 const pathname = window.location.origin + '/element-timing/resources/square100.png'; 18 // This method will check that entry.element is |img|. 19 checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img); 20 21 img.parentNode.removeChild(img); 22 // After removing image, entry.element should return null. 23 assert_equals(entry.element, null); 24 }) 25 ); 26 observer.observe({entryTypes: ['element']}); 27 // We add the image during onload to be sure that the observer is registered 28 // in time for it to observe the element timing. 29 window.onload = () => { 30 // Add image of width equal to 100 and height equal to 100. 31 img = document.createElement('img'); 32 img.src = 'resources/square100.png'; 33 img.setAttribute('elementtiming', 'my_image'); 34 img.setAttribute('id', 'my_id'); 35 document.body.appendChild(img); 36 beforeRender = performance.now(); 37 }; 38 }, 'Disconnected elements have null as their |element| attribute.'); 39 </script> 40 41 </body>