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 PerformanceObserverEntryList interface is a list of peformance events that were explicitly observed via the observe() method.

Note: this interface is exposed to Window and Worker.


Returns a list of explicitly observed PerformanceEntry objects based on the given filter.
Returns a list of explicitly observed PerformanceEntry objects of the given entry type.
Returns a list of explicitly observed PerformanceEntry objects based on the given name and entry type.


// Create observer for all performance event types 
// list is of type PerformanceObserveEntryList
var observe_all = new PerformanceObserver(function(list, obs) {  
   var perfEntries; 
   // Print all entries perfEntries = list.getEntries(); 
   for (var i=0; i < perfEntries.length; i++) { 
      // do something with it 


Specification Status Comment
Performance Timeline Time Level 2
The definition of 'PerformanceObserverEntryList' in that specification.
Editor's Draft Initial definition.

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) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support No support No support 49.0 (49)[1] No support 39 No support 52.0

[1] Only activated in Nightly builds. Controlled by the dom.enable_performance_observer preference. 


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API Interface Reference Web Performance