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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>
<img src=resources/slow-image.py?name=square20.png&sleep=500>
<script>
/*
In this test, a slow image is added to the frame to delay onload. The entry
is available from the observer with the buffered flag set to true.
*/
async_test(function(t) {
assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
beforeRender = performance.now();
const img = document.createElement('img');
img.src = 'resources/square20.jpg';
img.setAttribute('elementtiming', 'my_image');
img.setAttribute('id', 'my_id');
document.body.appendChild(img);
// this PerformanceObserver should be notified about the previously
// buffered element entry
new PerformanceObserver(t.step_func((entryList, observer) => {
assert_equals(entryList.getEntries().length, 1);
entryList.getEntries().forEach(entry => {
assert_equals(entry.entryType, "element");
const pathname = window.location.origin + '/element-timing/resources/square20.jpg';
checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img);
checkNaturalSize(entry, 20, 20);
observer.disconnect();
t.done();
});
})).observe({
type: "element",
buffered: true
});
}, "Element Timing: image loads before onload available from buffered flag.");
</script>
</body>
</html>
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