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.interactionCount")}} {{ReadOnlyInline}}
  • : The number of real-user interactions that have occurred on the page, which is useful when calculating {{Glossary("Interaction_to_next_paint", "Interaction to Next Paint (INP)")}}.
• {{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 an {{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

{{Compat}}