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<!DOCTYPE html>
<html>
<meta charset=utf-8 />
<title>Element Timing: buffer elements before onload</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src="resources/element-timing-helpers.js"></script>
<body>
<script>
let beforeRender;
let img;
// Number of characters to be read on the initial read, before sleeping.
// Should be sufficient to do at least a first scan.
let numInitial = 75;
let sleep = 500;
async_test(function(t) {
assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
const img_src = 'resources/progressive-image.py?name=square20.jpg&numInitial='
+ numInitial + '&sleep=' + sleep;
const observer = new PerformanceObserver(
t.step_func_done(function(entryList) {
assert_equals(entryList.getEntries().length, 1);
const entry = entryList.getEntries()[0];
const pathname = window.location.origin + '/element-timing/' + img_src;
// Since the image is only fully loaded after the sleep, the render timestamp
// must be greater than |beforeRender| + |sleep|.
checkElement(entry, pathname, 'my_image', '', beforeRender + sleep, img);
checkNaturalSize(entry, 20, 20);
})
);
observer.observe({entryTypes: ['element']});
img = document.createElement('img');
img.src = img_src;
img.setAttribute('elementtiming', 'my_image');
document.body.appendChild(img);
beforeRender = performance.now();
t.step_timeout(() => {assert_true(0);}, 2000);
}, "Element Timing: image render timestamp occurs after it is fully loaded.");
</script>
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