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   This deprecated API should no longer be used, but will probably still work.
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.

Not available in workers.

Performance.timing Read only   This deprecated API should no longer be used, but will probably still work.
A legacy PerformanceTiming object containing latency-related performance information.

Not available in workers.

Performance.memory Read only This API has not been standardized.
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   This API has not been standardized.
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 Status Comment
High Resolution Time Level 2
The definition of 'Performance' in that specification.
Recommendation Defines toJson() method.
High Resolution Time
The definition of 'Performance' in that specification.
Recommendation Defines now() method.
Performance Timeline Level 2
The definition of 'Performance extensions' in that specification.
Candidate Recommendation Changes getEntries() interface.
Performance Timeline
The definition of 'Performance extensions' in that specification.
Recommendation Defines getEntries(), getEntriesByType() and getEntriesByName() methods.
Resource Timing Level 1
The definition of 'Performance extensions' in that specification.
Candidate Recommendation Defines clearResourceTimings() and setResourceTimingBufferSize() methods and the onresourcetimingbufferfull property.
User Timing Level 2
The definition of 'Performance extensions' in that specification.
Working Draft Clarifies mark(), clearMark(), measure() and clearMeasure() methods.
User Timing
The definition of 'Performance extensions' in that specification.
Recommendation Defines mark(), clearMark(), measure() and clearMeasure() methods.

Browser compatibility

BCD tables only load in the browser