Performance

The Performance interface represents timing-related performance information for the given page.

An object of this type can be obtained by calling the Window.performance read-only attribute.

Note: This interface and its members are available in Web Workers, except where indicated below. Note that some available parts of the interface are not yet documented (see the Performance Timeline and User Timing specs for more details.) Also note that performance markers and measures are per context. If you create a mark on the main thread (or other worker), you cannot see it in a worker thread, and vice versa.

Properties

The Performance interface doesn't inherit any property.

Performance.timing Read only Not available to workers
Is a PerformanceTiming object containing latency-related performance information.
Performance.navigation Read only Not available to workers
Is a PerformanceNavigation object representing the type of navigation that occurs in the given browsing context, like the amount of redirections needed to fetch the resource.

Methods

The Performance interface doesn't inherit any method.

Performance.now()
Returns a DOMHighResTimeStamp representing the amount of milliseconds elapsed since a reference instant.
Performance.toJSON() Not available to workers
Is a jsonizer returning a json object representing the Performance object.

Specifications

Specification Status Comment
High Resolution Time
The definition of 'Performance' in that specification.
Recommendation Added the now() method.
Navigation Timing
The definition of 'Performance' in that specification.
Recommendation Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support (timing attribute) 6.0 7.0 (7.0) 9.0 15.0 8
navigation attribute 9 7 (7) 9.0 15 8
now() on regular context 20.0 webkit
24.0
15.0 (15.0) 10.0 (Yes) 8
now() in Web workers. 33.0 34.0 (34.0) ? (Yes) ?
toJSON() Not supported 25.0 (25.0) 9.0 Not supported ?
Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support Not supported 7.0 (7.0) 1.0 (7.0) 9.0 15.0 Not supported
navigation attribute Not supported Not supported Not supported 9.0 Not supported Not supported
now() on regular context 20.0 webkit
24.0
15.0 (15.0) 1.0 (15.0) 10.0 Not supported Not supported
now() in Web workers. ? 34.0 (34.0) ? ? ? ?
toJSON() Not supported 25.0 (25.0) 1.2 (25.0) 9.0 Not supported Not supported

See also

Document Tags and Contributors

Contributors to this page: Rob W, chrisdavidmills, adria, fscholz, zanona, Bzbarsky, teoli
Last updated by: Rob W,