Performance
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.
Note: This feature is available in Web 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 Window.performance
, and for code running in a worker via WorkerGlobalScope.performance
.
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 a
entryType
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
PerformanceEntry
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