The observe()
method of the PerformanceObserver
interface is used to specify the set of performance interface types to observe. The performance observer's callback function will be invoked when a performance entry is recorded for one of the specified types.
The types are specified in an array of strings
and the valid values are defined in PerformanceEntry.entryType
.
Syntax
observer.observe(options);
Parameters
- options
- A
PerformanceObserverInit
dictionary with one member:- "
entryTypes
", an array ofstrings
and the valid values for the strings are defined inPerformanceEntry.entryType
. If a value is not valid, the browser will ignore it. If theoptions
argument is not given or the array is empty,TypeError
is thrown.
- "
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 'observe()' in that specification. |
Editor's Draft | Initial definition of observe() method. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 52.0 | 57 (57) | 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 | 57.0 (57) | No support |
39 |
No support | 52.0 |