coderef

Long task performance entriesLimited availability

A longtask performance entry measures tasks that occupy the UI thread for 50 milliseconds or more, a metric for input latency, delayed animations, and other sources of "jank."

Not yet supported in all major browsers — check the table and provide a fallback.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–57Not supported
58+Supportedsince Apr 19, 2017
Current: 155
Edge
12–18Not supported
79+Supportedsince Jan 15, 2020
Current: 154
Firefox
✕Not supportedup to 157
Current: 157
Safari
✕Not supportedup to 27
Current: 27
MobileChrome Android
18–57Not supported
58+Supportedsince Apr 25, 2017
Current: 155
Firefox Android
✕Not supportedup to 157
Current: 157
Safari iOS
✕Not supportedup to 27
Current: 27

How to use

Not supported in Firefox, Safari, Firefox Android, Safari iOS. Use feature detection below and provide a fallback (or a polyfill) for those browsers.

Example

Full syntax and examples are on MDN: PerformanceLongTaskTiming.

Feature detection

JS · check before using
if ("PerformanceLongTaskTiming" in globalThis) {
  // PerformanceLongTaskTiming is available
} else {
  // load a polyfill or use a fallback
}

Documentation (MDN)

Specification

Sub-features

Support for each part of the feature (9). The overall table above shows when the whole feature works.

Sub-featureChromeEdgeFirefoxSafariChrome AndroidFirefox AndroidSafari iOS
PerformanceLongTaskTiming5879✕✕58✕✕
PerformanceLongTaskTiming.attribution5879✕✕58✕✕
PerformanceLongTaskTiming.toJSON5879✕✕58✕✕
TaskAttributionTiming5879✕✕58✕✕
TaskAttributionTiming.containerId5879✕✕58✕✕
TaskAttributionTiming.containerName5879✕✕58✕✕
TaskAttributionTiming.containerSrc5879✕✕58✕✕
TaskAttributionTiming.containerType5879✕✕58✕✕
TaskAttributionTiming.toJSON5879✕✕58✕✕