Performance

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.

Note: This feature is available in Web Workers.

The Performance 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 via Window.performance, and for code running in a worker via WorkerGlobalScope.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.
Performance.timing Read only Deprecated: A legacy PerformanceTiming object containing latency-related performance information.
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 PerformanceEntry 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 Level 3 # extensions-performance-interface

Browser compatibility

BCD tables only load in the browser