Performance
The Performance
interface provides access to performance-related information for the current page. It's part of the High Resolution Time API, but is enhanced by the Performance Timeline API, the Navigation Timing API, the User Timing API, and the Resource Timing API.
An object of this type can be obtained by calling the window.performance
read-only attribute.
Note: This interface and its members are available in Web Workers via WorkerGlobalScope.performance
, except where indicated below. Also, note that performance markers and measures are per context. If you create a mark on the main thread (or other worker), you cannot see it in a worker thread, and vice versa.
Properties
The Performance
interface doesn't inherit any properties.
-
A legacy
PerformanceNavigation
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.Note: Not available in workers.
Performance.timing
Read only-
A legacy
PerformanceTiming
object containing latency-related performance information.Note: Not available in workers.
Performance.memory
Read only-
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.
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 aentryType
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.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
performance entry
objects. Performance.toJSON()
-
Is a jsonizer returning a json object representing 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
BCD tables only load in the browser