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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.timingRead only Not available to workers- Is a
PerformanceTimingobject containing latency-related performance information. Performance.navigationRead only Not available to workers- Is a
PerformanceNavigationobject 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
DOMHighResTimeStamprepresenting the amount of milliseconds elapsed since a reference instant. Performance.toJSON()Not available to workers- Is a jsonizer returning a json object representing the
Performanceobject.
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
- Related interfaces:
PerformanceTiming,PerformanceNavigation.