PerformanceObserver

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.

* Some parts of this feature may have varying levels of support.

Note: This feature is available in Web Workers.

The PerformanceObserver interface is used to observe performance measurement events and be notified of new performance entries as they are recorded in the browser's performance timeline.

Constructor

PerformanceObserver()

Creates and returns a new PerformanceObserver object.

Static properties

PerformanceObserver.supportedEntryTypes Read only

Returns an array of the entryType values supported by the user agent.

Instance methods

PerformanceObserver.observe()

Specifies the set of entry types to observe. The performance observer's callback function will be invoked when performance entry is recorded for one of the specified entryTypes.

PerformanceObserver.disconnect()

Stops the performance observer callback from receiving performance entries.

PerformanceObserver.takeRecords()

Returns the current list of performance entries stored in the performance observer, emptying it out.

Examples

Creating a PerformanceObserver

The following example creates a PerformanceObserver watching for "mark" (PerformanceMark) and "measure" (PerformanceMeasure) events. The perfObserver callback provides a list (PerformanceObserverEntryList) which allows you to get observed performance entries.

js
function perfObserver(list, observer) {
  list.getEntries().forEach((entry) => {
    if (entry.entryType === "mark") {
      console.log(`${entry.name}'s startTime: ${entry.startTime}`);
    }
    if (entry.entryType === "measure") {
      console.log(`${entry.name}'s duration: ${entry.duration}`);
    }
  });
}
const observer = new PerformanceObserver(perfObserver);
observer.observe({ entryTypes: ["measure", "mark"] });

Specifications

Specification
Performance Timeline
# dom-performanceobserver

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
PerformanceObserver
PerformanceObserver() constructor
droppedEntriesCount() parameter
Experimental
disconnect
observe
supportedEntryTypes() static method
takeRecords
Available in workers

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
Partial support
Partial support
No support
No support
Experimental. Expect behavior to change in the future.
Has more compatibility info.

See also