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.

EventTarget Performance

Instance properties

The Performance interface doesn't inherit any properties.

Performance.eventCounts Read only

An EventCounts map containing the number of events which have been dispatched per event type.

Performance.navigation Read only Deprecated

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 Deprecated

A legacy PerformanceTiming object containing latency-related performance information.

Note: Not available in workers.

Performance.memory Read only Non-standard Deprecated

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.

Instance 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.measureUserAgentSpecificMemory() Experimental

Estimates the memory usage of a web application including all its iframes and workers.

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()

Returns a JSON representation of 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.

Specifications

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

Browser compatibility

BCD tables only load in the browser