Interface NodeEventTarget

The NodeEventTarget is a Node.js-specific extension to EventTarget that emulates a subset of the EventEmitter API.

Since

v14.5.0

interface NodeEventTarget {
    addListener(type: string, listener: ((arg: any) => void)): this;
    emit(type: string, arg: any): boolean;
    eventNames(): string[];
    listenerCount(type: string): number;
    setMaxListeners(n: number): void;
    getMaxListeners(): number;
    off(type: string, listener: ((arg: any) => void), options?: EventListenerOptions): this;
    on(type: string, listener: ((arg: any) => void)): this;
    once(type: string, listener: ((arg: any) => void)): this;
    removeAllListeners(type?: string): this;
    removeListener(type: string, listener: ((arg: any) => void), options?: EventListenerOptions): this;
    addEventListener(type: string, callback: null | EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
    dispatchEvent(event: Event): boolean;
    removeEventListener(type: string, callback: null | EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
}

Hierarchy

Methods

addListener emit eventNames listenerCount setMaxListeners getMaxListeners off on once removeAllListeners removeListener addEventListener dispatchEvent removeEventListener

Methods

addListener

  • addListener(type, listener): this

  • Node.js-specific extension to the EventTarget class that emulates the equivalent EventEmitter API. The only difference between addListener() and addEventListener() is that addListener() will return a reference to the EventTarget.

    Parameters

    • type: string
    • listener: ((arg: any) => void)
        • (arg): void

        • Parameters

          • arg: any

          Returns void

    Returns this

    Since

    v14.5.0

emit

  • emit(type, arg): boolean

  • Node.js-specific extension to the EventTarget class that dispatches the arg to the list of handlers for type.

    Parameters

    • type: string
    • arg: any

    Returns boolean

    true if event listeners registered for the type exist, otherwise false.

    Since

    v15.2.0

eventNames

  • eventNames(): string[]

  • Node.js-specific extension to the EventTarget class that returns an array of event type names for which event listeners are registered.

    Returns string[]

    Since

    14.5.0

listenerCount

  • listenerCount(type): number

  • Node.js-specific extension to the EventTarget class that returns the number of event listeners registered for the type.

    Parameters

    • type: string

    Returns number

    Since

    v14.5.0

setMaxListeners

  • setMaxListeners(n): void

  • Node.js-specific extension to the EventTarget class that sets the number of max event listeners as n.

    Parameters

    • n: number

    Returns void

    Since

    v14.5.0

getMaxListeners

  • getMaxListeners(): number

  • Node.js-specific extension to the EventTarget class that returns the number of max event listeners.

    Returns number

    Since

    v14.5.0

off

  • off(type, listener, options?): this

  • Node.js-specific alias for eventTarget.removeEventListener().

    Parameters

    • type: string
    • listener: ((arg: any) => void)
        • (arg): void

        • Parameters

          • arg: any

          Returns void

    • Optionaloptions: EventListenerOptions

    Returns this

    Since

    v14.5.0

on

  • on(type, listener): this

  • Node.js-specific alias for eventTarget.addEventListener().

    Parameters

    • type: string
    • listener: ((arg: any) => void)
        • (arg): void

        • Parameters

          • arg: any

          Returns void

    Returns this

    Since

    v14.5.0

once

  • once(type, listener): this

  • Node.js-specific extension to the EventTarget class that adds a once listener for the given event type. This is equivalent to calling on with the once option set to true.

    Parameters

    • type: string
    • listener: ((arg: any) => void)
        • (arg): void

        • Parameters

          • arg: any

          Returns void

    Returns this

    Since

    v14.5.0

removeAllListeners

  • removeAllListeners(type?): this

  • Node.js-specific extension to the EventTarget class. If type is specified, removes all registered listeners for type, otherwise removes all registered listeners.

    Parameters

    • Optionaltype: string

    Returns this

    Since

    v14.5.0

removeListener

  • removeListener(type, listener, options?): this

  • Node.js-specific extension to the EventTarget class that removes the listener for the given type. The only difference between removeListener() and removeEventListener() is that removeListener() will return a reference to the EventTarget.

    Parameters

    • type: string
    • listener: ((arg: any) => void)
        • (arg): void

        • Parameters

          • arg: any

          Returns void

    • Optionaloptions: EventListenerOptions

    Returns this

    Since

    v14.5.0

addEventListener

  • addEventListener(type, callback, options?): void

  • Appends an event listener for events whose type attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.

    The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options's capture.

    When set to true, options's capture prevents callback from being invoked when the event's eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event's eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event's eventPhase attribute value is AT_TARGET.

    When set to true, options's passive indicates that the callback will not cancel the event by invoking preventDefault(). This is used to enable performance optimizations described in ยง 2.8 Observing event listeners.

    When set to true, options's once indicates that the callback will only be invoked once after which the event listener will be removed.

    If an AbortSignal is passed for options's signal, then the event listener will be removed when signal is aborted.

    The event listener is appended to target's event listener list and is not appended if it has the same type, callback, and capture.

    MDN Reference

    Parameters

    Returns void

dispatchEvent

  • dispatchEvent(event): boolean

  • Dispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.

    MDN Reference

    Parameters

    Returns boolean

removeEventListener

  • removeEventListener(type, callback, options?): void

  • Removes the event listener in target's event listener list with the same type, callback, and options.

    MDN Reference

    Parameters

    Returns void

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