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<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: observe elements with elementtiming attribute</title>
<body>
<style>
body {
margin: 0;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<script>
let beforeRender;
let img;
async_test(function (t) {
assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
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/resources/square100.png';
checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img);
// Assume viewport has size at least 100, so the element is fully visible.
checkRect(entry, [0, 100, 0, 100]);
checkNaturalSize(entry, 100, 100);
})
);
observer.observe({entryTypes: ['element']});
// We add the image during onload to be sure that the observer is registered
// in time for it to observe the element timing.
window.onload = () => {
// Add image of width equal to 100 and height equal to 100.
img = document.createElement('img');
img.src = 'resources/square100.png';
img.setAttribute('elementtiming', 'my_image');
img.setAttribute('id', 'my_id');
document.body.appendChild(img);
beforeRender = performance.now();
};
}, 'Element with elementtiming attribute is observable.');
</script>
</body>
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