This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The PerformanceObserver()
constructor creates a new PerformanceObserver
object with the given observer callback
. The observer callback is invoked when performance entry events are recorded for the entry types that have been registered, via the observe()
method.
Syntax
var observer = new PerformanceObserver(callback);
Parameters
callback
- A
PerformanceObserverCallback
callback that will be invoked when observered performance events are recorded. When the callback is invoked, its first parameter is a list of performance observer entries and the second parameter is theobserver
object.
Example
var observer = new PerformanceObserver(function(list, obj) { var entries = list.getEntries(); for (var i=0; i < entries.length; i++) { // Process "mark" and "frame" events } }); observer.observe({entryTypes: ["mark", "frame"]}); function perf_observer(list, observer) { // Process the "measure" event } var observer2 = new PerformanceObserver(perf_observer); observer2.observe({entryTypes: ["measure"]});
Specifications
Specification | Status | Comment |
---|---|---|
Performance Timeline Time Level 2 The definition of 'PerformanceObserver()' in that specification. |
Editor's Draft | Initial definition of PerformanceObserver() constructor. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 52.0 | 49 (49)[1] | No support | 39 | No support |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | No support | No support | 49 (49)[1] | No support | No support |
39 |
No support | 52.0 |
[1] Only activated in Nightly builds. Controlled by the dom.enable_performance_observer
preference.