ThePerformance interface provides access to performance-related information for the current page.

Performance entries are specific to each execution context. You can access performance information for code running in a window viaWindow.performance, and for code running in a worker viaWorkerGlobalScope.performance.

Instance properties

ThePerformance interface doesn't inherit any properties.

Performance.eventCountsRead only

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

Performance.navigationRead onlyDeprecated

A legacyPerformanceNavigation object that provides useful context about the operations included in the times listed intiming, including whether the page was a load or a refresh, how many redirections occurred, and so forth.

Performance.timingRead onlyDeprecated

A legacyPerformanceTiming object containing latency-related performance information.

Performance.memoryRead onlyNon-standardDeprecated

Anon-standard extension added in Chrome, this property provides an object with basic memory usage information.Youshould not use this non-standard API.

Performance.timeOriginRead only

Returns the high resolution timestamp of the start time of the performance measurement.

Instance methods

ThePerformance interface doesn't inherit any methods.

Performance.clearMarks()

Removes the givenmark from the browser's performance entry buffer.

Performance.clearMeasures()

Removes the givenmeasure from the browser's performance entry buffer.

Performance.clearResourceTimings()

Removes allperformance entries with aentryType of"resource" from the browser's performance data buffer.

Performance.getEntries()

Returns a list ofPerformanceEntry objects based on the givenfilter.

Performance.getEntriesByName()

Returns a list ofPerformanceEntry objects based on the givenname andentry type.

Performance.getEntriesByType()

Returns a list ofPerformanceEntry objects of the givenentry type.

Performance.mark()

Creates atimestamp in the browser'sperformance entry buffer with the given name.

Performance.measure()

Creates a namedtimestamp in the browser's performance entry buffer between two specified marks (known as thestart mark andend mark, respectively).

Performance.measureUserAgentSpecificMemory()Experimental

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

Performance.now()

Returns aDOMHighResTimeStamp 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"typePerformanceEntry objects.

Performance.toJSON()

Returns a JSON representation of thePerformance object.

Events

Listen to these events usingaddEventListener() or by assigning an event listener to theoneventname property of this interface.

resourcetimingbufferfull

Fired when the browser'sresource timing buffer is full.

Specifications

Browser compatibility