mirror of
https://github.com/servo/servo.git
synced 2025-07-11 17:33:47 +01:00
39 lines
1.5 KiB
HTML
39 lines
1.5 KiB
HTML
<!DOCTYPE HTML>
|
|
<meta charset=utf-8>
|
|
<title>Layout Jank: query jank 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) {
|
|
// Modify the position of the div.
|
|
document.getElementById('myDiv').style = "top: 60px";
|
|
function testBufferedEntry() {
|
|
if (performance.getEntriesByType('layoutJank').length === 0) {
|
|
t.step_timeout(testBufferedEntry, 0);
|
|
return;
|
|
}
|
|
assert_equals(performance.getEntriesByType('layoutJank').length, 1);
|
|
assert_equals(performance.getEntries().filter(
|
|
entry => entry.entryType === 'layoutJank').length, 1);
|
|
const entry = performance.getEntriesByType('layoutJank')[0];
|
|
assert_equals(entry.entryType, "layoutJank");
|
|
assert_equals(entry.name, "");
|
|
assert_equals(entry.startTime, 0.0);
|
|
assert_equals(entry.duration, 0.0);
|
|
// The layout jank fraction should be: 300 * (100 + 60) / viewport size.
|
|
assert_equals(entry.fraction, 300 * (100 + 60) /
|
|
(document.documentElement.clientWidth * document.documentElement.clientHeight));
|
|
t.done();
|
|
}
|
|
t.step(testBufferedEntry);
|
|
}, 'LayoutJank before onload is buffered into the performance timeline.');
|
|
</script>
|
|
|
|
</body>
|