Performance

{{APIRef("Performance API")}} {{AvailableInWorkers}} 

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 {{domxref("Window.performance")}} , and for code running in a worker via {{domxref("WorkerGlobalScope.performance")}} .

{{InheritanceDiagram}} 

Instance properties

The Performance interface doesn’t inherit any properties.

• {{domxref("Performance.eventCounts")}}  {{ReadOnlyInline}} 

  • : An {{domxref("EventCounts")}}  map containing the number of events which have been dispatched per event type.

• {{domxref("Performance.navigation")}}  {{ReadOnlyInline}}  {{Deprecated_Inline}} 

  • : A legacy {{domxref("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.

• {{domxref("Performance.timing")}}  {{ReadOnlyInline}}  {{Deprecated_Inline}} 

  • : A legacy {{domxref("PerformanceTiming")}}  object containing latency-related performance information.

• {{domxref("Performance.memory")}}  {{ReadOnlyInline}}  {{Non-standard_Inline}}  {{Deprecated_Inline}} 

  • : 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.

• {{domxref("Performance.timeOrigin")}}  {{ReadOnlyInline}} 

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

Instance methods

The Performance interface doesn’t inherit any methods.

• {{domxref("Performance.clearMarks()")}} 
  • : Removes the given mark from the browser’s performance entry buffer.
• {{domxref("Performance.clearMeasures()")}} 
  • : Removes the given measure from the browser’s performance entry buffer.
• {{domxref("Performance.clearResourceTimings()")}} 
  • : Removes all performance entries with a {{domxref("PerformanceEntry.entryType","entryType")}}  of "resource" from the browser’s performance data buffer.
• {{domxref("Performance.getEntries()")}} 
  • : Returns a list of {{domxref("PerformanceEntry")}}  objects based on the given filter.
• {{domxref("Performance.getEntriesByName()")}} 
  • : Returns a list of {{domxref("PerformanceEntry")}}  objects based on the given name and entry type.
• {{domxref("Performance.getEntriesByType()")}} 
  • : Returns a list of {{domxref("PerformanceEntry")}}  objects of the given entry type.
• {{domxref("Performance.mark()")}} 
  • : Creates a {{domxref("DOMHighResTimeStamp","timestamp")}}  in the browser’s performance entry buffer with the given name.
• {{domxref("Performance.measure()")}} 
  • : Creates a named {{domxref("DOMHighResTimeStamp","timestamp")}}  in the browser’s performance entry buffer between two specified marks (known as the start mark and end mark, respectively).
• {{domxref("Performance.measureUserAgentSpecificMemory()")}}  {{Experimental_Inline}} 
  • : Estimates the memory usage of a web application including all its iframes and workers.
• {{domxref("Performance.now()")}} 
  • : Returns a {{domxref("DOMHighResTimeStamp")}}  representing the number of milliseconds elapsed since a reference instant.
• {{domxref("Performance.setResourceTimingBufferSize()")}} 
  • : Sets the browser’s resource timing buffer size to the specified number of "resource" {{domxref("PerformanceEntry.entryType","type")}}  {{domxref("PerformanceEntry")}}  objects.
• {{domxref("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.

• {{DOMxRef("Performance.resourcetimingbufferfull_event", "resourcetimingbufferfull")}} 
  • : Fired when the browser’s resource timing buffer is full.

Specifications

{{Specifications}} 

Browser compatibility

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