servo/tests/wpt/web-platform-tests/performance-timeline/webtiming-resolution.html

35 lines
993 B
HTML

<!DOCTYPE HTML>
<html>
<head>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<script>
function testTimeResolution(highResTimeFunc, funcString) {
test(() => {
const t0 = highResTimeFunc();
let t1 = highResTimeFunc();
while (t0 == t1) {
t1 = highResTimeFunc();
}
assert_greater_than_equal(t1 - t0, 0.02, 'The second ' + funcString + ' should be much greater than the first');
}, 'Verifies the resolution of ' + funcString + ' is at least 20 microseconds.');
}
function timeByPerformanceNow() {
return performance.now();
}
function timeByUserTiming() {
performance.mark('timer');
const time = performance.getEntriesByName('timer')[0].startTime;
performance.clearMarks('timer');
return time;
}
testTimeResolution(timeByPerformanceNow, 'performance.now()');
testTimeResolution(timeByUserTiming, 'entry.startTime');
</script>
</body>
</html>