Content - 1723c293da8e7016955ea3857a6fb963f2145e76 - d50ea38/performance-timeline/webtiming-resolution.html

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Tip revision: f5bb782c766f17893c02dea2539281efb173f551 authored by Han Leon on 13 May 2018, 12:29:46 UTC
[ServiceWorker] Propagate change for ServiceWorkerRegistration#updateViaCache

Tip revision: f5bb782

webtiming-resolution.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>

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