Performance

The Performance interface provides access to performance-related information for the current page. It's part of the High Resolution Time API, but is enhanced by the Performance Timeline API, the Navigation Timing API, the User Timing API, and the Resource Timing API.

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 via WorkerGlobalScope.performance , except where indicated below. 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 properties.

Performance.navigation Read only: A legacy PerformanceNavigation object that provides useful context about the operations included in the times listed in timing, including whether the page was a load or a refresh, how many redirections occurred, and so forth.

Note: Not available in workers.
Performance.timing Read only: A legacy PerformanceTiming object containing latency-related performance information.

Note: Not available in workers.
Performance.memory Read only: A non-standard extension added in Chrome, this property provides an object with basic memory usage information. You should not use this non-standard API.
Performance.timeOrigin Read only: Returns the high resolution timestamp of the start time of the performance measurement.

Methods

The Performance interface doesn't inherit any methods.

Performance.clearMarks(): Removes the given mark from the browser's performance entry buffer.
Performance.clearMeasures(): Removes the given measure from the browser's performance entry buffer.
Performance.clearResourceTimings(): Removes all performance entries with a entryType of "resource" from the browser's performance data buffer.
Performance.getEntries(): Returns a list of PerformanceEntry objects based on the given filter.
Performance.getEntriesByName(): Returns a list of PerformanceEntry objects based on the given name and entry type.
Performance.getEntriesByType(): Returns a list of PerformanceEntry objects of the given entry type.
Performance.mark(): Creates a timestamp in the browser's performance entry buffer with the given name.
Performance.measure(): Creates a named timestamp in the browser's performance entry buffer between two specified marks (known as the start mark and end mark, respectively).
Performance.now(): Returns a DOMHighResTimeStamp representing the number of milliseconds elapsed since a reference instant.
Performance.setResourceTimingBufferSize(): Sets the browser's resource timing buffer size to the specified number of "resource" type performance entry objects.
Performance.toJSON(): Is a jsonizer returning a json object representing the Performance object.

Events

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface.

resourcetimingbufferfull: Fired when the browser's resource timing buffer is full. Also available via the onresourcetimingbufferfull property.

Specifications

Specification
High Resolution Time # sec-performance
Performance Timeline Level 2 (Performance Timeline 2) # extensions-to-the-performance-interface
Resource Timing Level 2 (Resource Timing 2) # sec-extensions-performance-interface
User Timing Level 2 (User Timing 2) # extensions-performance-interface

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`Performance`	6	12	7	9	15	8	≤37	18	7	14	9	1.0
`clearMarks`	29 25-29	12	41	10	33	11	≤37	29 25-29	42	33	11	2.0 1.5-2.0
`clearMeasures`	29 25-29	12	41	10	33	11	≤37	29 25-29	42	33	11	2.0 1.5-2.0
`clearResourceTimings`	46 22-57	12	35	10	Yes	11	46 ≤37-57	46 25-57	35	Yes	11	5.0 1.5-7.0
`eventCounts`	85	85	No	No	71	No	85	85	No	60	No	14.0
`getEntries`	28 25-36	12	35	10	No	11	≤37	28 25-36	35	No	11	1.5 1.5-3.0
`getEntriesByName`	28 25-36	12	35	10	No	11	≤37	28 25-36	35	No	11	1.5 1.5-3.0
`getEntriesByType`	28 25-36	12	35	10	15 15-23	11	≤37	28 25-36	35	15 14-24	11	1.5 1.5-3.0
`mark`	28 25-28	12	41	10	33	11	≤37	28 25-28	42	33	11	1.5
`measure`	28 25-28	12	41	10	33	11	≤37	28 25-28	42	33	11	1.5
`measureUserAgentSpecificMemory`	89	89	No	No	75	No	89	89	No	63	No	No
`memory`	7	79	No	No	Yes	No	≤37	18	No	Yes	No	1.0
`navigation`	10	12	7	9	15	8	≤37	18	7	No	9	1.0
`now`	24 21-24	12	15 ["In Firefox 57.0.4 the accuracy was reduced to 20 microseconds.", "In Firefox 59 the accuracy was reduced to 2 milliseconds.", "In Firefox 60 the accuracy was increased to 1 millisecond."]	10	15	8	≤37	25	15 ["In Firefox 57.0.4 the accuracy was reduced to 20 microseconds.", "In Firefox 59 the accuracy was reduced to 2 milliseconds.", "In Firefox 60 the accuracy was increased to 1 millisecond."]	14	9	1.5
`onresourcetimingbufferfull`	46 22-57	79	35	No	No	11	46 ≤37-57	46 25-57	35	Yes	No	5.0 1.5-7.0
`resourcetimingbufferfull_event`	46 22-57	79	Yes	No	No	11	46 ≤37-57	46 25-57	Yes	Yes	No	5.0 1.5-7.0
`setResourceTimingBufferSize`	46 22-57	12	35	10	Yes	11	46 ≤37-57	46 25-57	35	Yes	No	5.0 1.5-7.0
`timeOrigin`	62	16	53	No	49	preview	62	62	53	46	No	8.0
`timing`	6	12	7	9	15	8	≤37	18	7	14	9	1.0
`toJSON`	56	12	25	9	No	14.1	56	56	25	No	14.5	6.0

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https://developer.mozilla.org/en-US/docs/Web/API/Performance