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Event timing

The EventCounts interface of the Performance API provides the number of events that have been dispatched for each event type.

An EventCounts instance is a read-only Map-like object, in which each key is the name string for an event type, and the corresponding value is an integer indicating the number of events that have been dispatched for that event type.

Observers and Performance

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
EventCounts
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@@iterator

[Symbol.iterator]
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entries
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forEach
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get
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has
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keys
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size
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values
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eventCounts

The read-only performance.eventCounts property is an EventCounts map containing the number of events which have been dispatched per event type since the page was loaded.
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PerformanceEventTiming

The PerformanceEventTiming interface of the Event Timing API provides insights into the latency of certain event types triggered by user interaction.
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cancelable

The read-only cancelable property returns the associated event's cancelable property, indicating whether the event can be canceled.
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interactionId

The read-only interactionId property of the PerformanceEventTiming interface returns an ID that uniquely identifies a user interaction which triggered a series of associated events.
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processingEnd

The read-only processingEnd property returns the time the last event handler finished executing.
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processingStart

The read-only processingStart property returns the time at which event dispatch started. This is when event handlers are about to be executed.
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target

The read-only target property returns the associated event's last target which is the node onto which the event was last dispatched.
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toJSON

The toJSON() method of the PerformanceEventTiming interface is a Serialization; it returns a JSON representation of the PerformanceEventTiming object.
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1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)

Use cases

  • Using Event timing

    The EventCounts interface of the Performance API provides the number of events that have been dispatched for each event type.

Cautions

  • May not be supported in older browsers.

Implementation notes

  • Some APIs require a secure context (HTTPS) or user activation. Check the requirements before use.

Related links