Performance

Available in 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 performance, and for code running in a worker via performance.

Instance properties

The Performance interface doesn’t inherit any properties.

• eventCounts Read only
  • : An EventCounts map containing the number of events which have been dispatched per event type.
• interactionCount Read only
  • : The number of real-user interactions that have occurred on the page, which is useful when calculating Interaction to Next Paint (INP).
• 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.
• timing Read only Deprecated
  • : A legacy PerformanceTiming object containing latency-related performance information.
• memory Read only 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.
• 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.

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

Browser compatibility