Performance
The Performance
interface provides access to performance-related information for the current page.
An object of this type can be obtained by calling window.performance
or self.performance
in workers. Note that Performance entries 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. See self.performance
for which APIs are available in window and worker contexts.
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. -
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. 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 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.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
performance entry
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
Browser compatibility
BCD tables only load in the browser