Class Performance
- Namespace
- CSharpToJavaScript.APIs.JS
- Assembly
- CSharpToJavaScript.dll
The Performance interface provides access to performance-related information for the current page.
[Value("Performance")]
public class Performance : EventTarget- Inheritance
-
Performance
- Inherited Members
Remarks
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.
Constructors
Performance()
public Performance()Properties
EventCounts
The read-only performance.eventCounts property is an EventCounts map containing the number of events which have been dispatched per event type.
[Value("eventCounts")]
public EventCounts EventCounts { get; }Property Value
- EventCounts
An EventCounts map.
(A read-only Map without theclear(),delete(), andset()methods).
Remarks
Not all event types are exposed. You can only get counts for event types supported by the PerformanceEventTiming interface.
InteractionCount
[Value("interactionCount")]
public ulong InteractionCount { get; }Property Value
Navigation
IMPORTANT
DeprecatedPerformance.navigationread-only property returns a PerformanceNavigation object representing
the type of navigation that occurs in the given browsing context, such as the number of
redirections needed to fetch the resource.
[Value("navigation")]
public PerformanceNavigation Navigation { get; }Property Value
- PerformanceNavigation
A PerformanceNavigation object.
Remarks
This property is not available in workers.
WARNING
This property is deprecated in the Navigation Timing Level 2 specification. Please use the
PerformanceNavigationTiming interface instead.
-The Performance interface it belongs to.
Onresourcetimingbufferfull
[Value("onresourcetimingbufferfull")]
public EventHandlerNonNull Onresourcetimingbufferfull { get; set; }Property Value
TimeOrigin
The timeOrigin read-only property of the Performance interface returns the high resolution timestamp that is used as the baseline for performance-related timestamps.
[Value("timeOrigin")]
public Number TimeOrigin { get; }Property Value
- Number
A high resolution timestamp which considered to be the beginning of the current document's lifetime. It's calculated like this:
Remarks
In Window contexts, this value represents the time when navigation has started. In Worker and ServiceWorker contexts, this value represents the time when the worker is run. You can use this property to synchronize the time origins between the contexts (see example below).
NOTE
The value of
performance.timeOriginmay differ from the value returned by DateNow executed at the time origin, becauseDate.now()may have been impacted by system and user clock adjustments, clock skew, etc. ThetimeOriginproperty is a monotonic clock which current time never decreases and which isn't subject to these adjustments.
Timing
IMPORTANT
DeprecatedPerformance.timing read-onlyproperty returns a PerformanceTiming object containing latency-related
performance information.
[Value("timing")]
public PerformanceTiming Timing { get; }Property Value
- PerformanceTiming
A PerformanceTiming object.
Remarks
This property is not available in workers.
WARNING
This property is deprecated in the Navigation Timing Level 2 specification. Please use the PerformanceNavigationTiming
interface instead.
-The Performance interface it belongs to.
Methods
ClearMarks(string)
The clearMarks() method removes all or specific PerformanceMark objects from the browser's performance timeline.
[Value("clearMarks")]
public GlobalObject.Undefined ClearMarks(string markName = null)Parameters
markNamestring
Returns
Remarks
ClearMeasures(string)
The clearMeasures() method removes all or specific PerformanceMeasure objects from the browser's performance timeline.
[Value("clearMeasures")]
public GlobalObject.Undefined ClearMeasures(string measureName = null)Parameters
measureNamestring
Returns
Remarks
ClearResourceTimings()
The clearResourceTimings() method removes all performance entries with an EntryType of "resource" from the browser's performance timeline and sets the size of the performance resource data buffer to zero.
[Value("clearResourceTimings")]
public GlobalObject.Undefined ClearResourceTimings()Returns
Remarks
To set the size of the browser's performance resource data buffer, use the
SetResourceTimingBufferSize(ulong) method.
To get notified when the browser's resource timing buffer is full, listen for the Performance.Resourcetimingbufferfull event.
-SetResourceTimingBufferSize(ulong)
-Performance.Resourcetimingbufferfull
GetEntries()
The getEntries() method returns an array of all PerformanceEntry objects currently present in the performance timeline.
[Value("getEntries")]
public List<PerformanceEntry> GetEntries()Returns
- List<PerformanceEntry>
An {{jsxref("Array")}} of PerformanceEntry objects. The items will be in chronological order based on the entries' StartTime.
Remarks
If you are only interested in performance entries of certain types or that have certain names, see GetEntriesByType(string) and GetEntriesByName(string, string).
NOTE
This method does not notify you about new performance entries; you will only get entries that are present in the performance timeline at the time you call this method.
To receive notifications about entries as they become available, use a PerformanceObserver.
The following entry types are not supported by this method at all and won't be returned even if entries for these types might exist:
To access entries of these types, you must use a PerformanceObserver instead.
GetEntriesByName(string, string)
The getEntriesByName() method returns an array of PerformanceEntry objects currently present in the performance timeline with the given name and type.
[Value("getEntriesByName")]
public List<PerformanceEntry> GetEntriesByName(string name, string type = null)Parameters
Returns
- List<PerformanceEntry>
An {{jsxref("Array")}} of PerformanceEntry objects that have the specified
nameandtype.
The items will be in chronological order based on the entries' StartTime. If no objects meet the
specified criteria, an empty array is returned.
Remarks
If you are interested in performance entries of certain types, see GetEntriesByType(string). For all performance entries, see GetEntries().
NOTE
This method does not notify you about new performance entries; you will only get entries that are present in the performance timeline at the time you call this method.
To receive notifications about entries as they become available, use a PerformanceObserver.
The following entry types are not supported by this method at all and won't be returned even if entries for these types might exist:
To access entries of these types, you must use a PerformanceObserver instead.
GetEntriesByType(string)
The getEntriesByType() method returns an array of PerformanceEntry objects currently present in the performance timeline for a given type.
[Value("getEntriesByType")]
public List<PerformanceEntry> GetEntriesByType(string type)Parameters
typestring
Returns
- List<PerformanceEntry>
An {{jsxref("Array")}} of PerformanceEntry objects that have the specified
type. The items will be in chronological order based on the entries' StartTime. If no objects have the specifiedtype, or no argument is provided, an empty array is returned.
Remarks
If you are interested in performance entries of certain name, see GetEntriesByName(string, string). For all performance entries, see GetEntries().
NOTE
This method does not notify you about new performance entries; you will only get entries that are present in the performance timeline at the time you call this method.
To receive notifications about entries as they become available, use a PerformanceObserver.
The following entry types are not supported by this method at all and won't be returned even if entries for these types might exist:
To access entries of these types, you must use a PerformanceObserver instead.
-GetEntries()
-GetEntriesByName(string, string)
-SupportedEntryTypes
Mark(string, PerformanceMarkOptions)
The mark() method creates a named PerformanceMark object representing a high resolution timestamp marker in the browser's performance timeline.
[Value("mark")]
public PerformanceMark Mark(string markName, PerformanceMarkOptions markOptions = null)Parameters
markNamestringmarkOptionsPerformanceMarkOptions
Returns
- PerformanceMark
The PerformanceMark entry that was created.
Remarks
Measure(string, Union158, string)
The measure() method creates a named PerformanceMeasure object representing a time measurement between two marks in the browser's performance timeline.
[Value("measure")]
public PerformanceMeasure Measure(string measureName, Union158 startOrMeasureOptions = default, string endMark = null)Parameters
Returns
- PerformanceMeasure
The PerformanceMeasure entry that was created.The returned measure will have the following property values:
Remarks
When measuring between two marks, there is a start mark and end mark, respectively.
The named timestamp is referred to as a measure.
MeasureUserAgentSpecificMemory()
NOTE
ExperimentalmeasureUserAgentSpecificMemory() method is used to estimate the memory usage of a web application including all its iframes and workers.
[Value("measureUserAgentSpecificMemory")]
public Task<MemoryMeasurement> MeasureUserAgentSpecificMemory()Returns
- Task<MemoryMeasurement>
A Promise that resolves to an object containing the following properties:An example return value looks like this:
Remarks
-Window.SetTimeout
-Monitor your web page's total memory usage with measureUserAgentSpecificMemory() - web.dev
Now()
The performance.now() method returns a high resolution timestamp in milliseconds. It represents the time elapsed since TimeOrigin (the time when navigation has started in window contexts, or the time when the worker is run in Worker and ServiceWorker contexts).
[Value("now")]
public Number Now()Returns
Remarks
SetResourceTimingBufferSize(ulong)
The setResourceTimingBufferSize() method sets the desired size of the browser's resource timing buffer which stores the "resource" performance entries.
[Value("setResourceTimingBufferSize")]
public GlobalObject.Undefined SetResourceTimingBufferSize(ulong maxSize)Parameters
maxSizeulong
Returns
Remarks
The specification requires the resource timing buffer initially to be 250 or greater.
To clear the browser's performance resource data buffer, use the
ClearResourceTimings() method.
To get notified when the browser's resource timing buffer is full, listen for the Performance.Resourcetimingbufferfull event.
-ClearResourceTimings()
-Performance.Resourcetimingbufferfull
ToJSON()
The toJSON() method of the Performance interface is a {{Glossary("Serialization","serializer")}}; it returns a JSON representation of the Performance object.
[Value("toJSON")]
public Object ToJSON()Returns
- Object
A {{jsxref("JSON")}} object that is the serialization of the Performance object.The returned JSON doesn't contain the EventCounts property because it is of type EventCounts, which doesn't provide a
toJSON()operation.NOTE
The JSON object contains the serialization of the deprecated Timing and Navigation properties. To get a JSON representation of the newer PerformanceNavigationTiming interface, call ToJSON() instead.