blob: 0cfce2f7124226cf4256284c1238ba1ef024c42b [file] [log] [blame]
<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Layout Instability entries are not available via the performance timeline</title>
<body>
<style>
#myDiv { position: relative; width: 300px; height: 100px; }
</style>
<div id='myDiv'></div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<!-- Delay onload by inserting a slow image.-->
<img src="resources/slow-image.py">
<script>
async_test(function (t) {
if (!window.LayoutShift)
assert_unreached('LayoutShift entries are not supported');
const startTime = performance.now();
new PerformanceObserver(list => {
const endTime = performance.now();
assert_equals(list.getEntries().length, 1);
const entry = list.getEntries()[0];
assert_equals(entry.entryType, "layout-shift");
assert_equals(entry.name, "");
assert_greater_than_equal(entry.startTime, startTime)
assert_less_than_equal(entry.startTime, endTime)
assert_equals(entry.duration, 0.0);
const maxDimension = Math.max(document.documentElement.clientWidth,
document.documentElement.clientHeight);
// The layout shift value should be:
// 300 * (100 + 60) * (60 / maxDimension) / viewport size.
assert_equals(entry.value, 300 * (100 + 60) * (60 / maxDimension) /
(document.documentElement.clientWidth * document.documentElement.clientHeight));
// The entry should not be available via getEntries* methods.
assert_equals(performance.getEntriesByType('layout-shift').length, 0, 'getEntriesByType should have no layout-shift entries');
assert_equals(performance.getEntriesByName('', 'layout-shift').length, 0, 'getEntriesByName should have no layout-shift entries');
assert_equals(performance.getEntries().filter(e => e.entryType === 'layout-shift').length, 0, 'getEntries should have no layout-shift entries');
t.done();
}).observe({type: 'layout-shift'});
// Modify the position of the div.
document.getElementById('myDiv').style = "top: 60px";
}, 'Layout shift before onload is not buffered into the performance timeline.');
</script>
</body>