Emitter <Events>

Cross-platform, lightweight type-safe event emitter.

@example

type Events = {
  error: (error: Error) => void
  message: (from: string, content: string) => void
}

const emitter = new Emitter<Events>()
emitter.emit('error', 'x')  // will catch this type error

Implements

• TypedEventEmitter<Events>

Index

Constructors

• constructor

Methods

• emit
• eventNames
• listenerCount
• listeners
• off
• on
• once
• removeAllListeners

Constructors

constructor

• new Emitter<Events>(): Emitter<Events>

• Type parameters

  • Events: EventMap

  Returns Emitter<Events>

Methods

emit

• emit<Event>(event: Event, ...args: Parameters<Events[Event]>): boolean

• Implementation of TypedEventEmitter.emit

  Emits an event with a given name and passes any number of arguments to the listeners. Returns a boolean indicating whether the event had listeners attached.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    The name of the event to be emitted.

  • rest...args: Parameters<Events[Event]>

    Any number of arguments to be passed to the listeners.

  Returns boolean

  A boolean indicating whether the event had listeners attached.

eventNames

• eventNames(): (string | symbol | keyof Events)[]

• Implementation of TypedEventEmitter.eventNames

  Returns an array of all the event names that have listeners.

  ---

  Returns (string | symbol | keyof Events)[]

  An array of event names.

listenerCount

• listenerCount<Event>(event: Event): number

• Implementation of TypedEventEmitter.listenerCount

  Returns the number of listeners for the given event.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    The event name.

  Returns number

  The number of listeners for the given event.

listeners

• listeners<Event>(event: Event): Events[Event][]

• Implementation of TypedEventEmitter.listeners

  Returns an array of listeners for the specified event.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    The event name to retrieve listeners for.

  Returns Events[Event][]

  An array of listeners for the specified event.

off

• off<Event>(event: Event, listener: Events[Event]): this

• Implementation of TypedEventEmitter.off

  Removes a listener from the specified event.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    the event to remove the listener from.

  • listener: Events[Event]

    the listener to remove from the event.

  Returns this

  The class instance for chaining.

on

• on<Event>(event: Event, listener: Events[Event]): this

• Implementation of TypedEventEmitter.on

  Adds a listener for the specified event.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    The event name.

  • listener: Events[Event]

    The listener function.

  Returns this

  Returns this instance for chaining.

once

• once<Event>(event: Event, listener: Events[Event]): Events[Event]

• Implementation of TypedEventEmitter.once

  Returns a proxy function that when called, invokes the original listener function and removes the listener from the event emitter.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • event: Event

    The event to listen to.

  • listener: Events[Event]

    The listener function to be called once.

  Returns Events[Event]

  The original listener function.

removeAllListeners

• removeAllListeners<Event>(event?: Event): this

• Implementation of TypedEventEmitter.removeAllListeners

  Removes all listeners for the specified event or all events if none specified.

  ---

  Type parameters

  • Event: string | number | symbol

  Parameters

  • optionalevent: Event

    The event to remove listeners for.

  Returns this

  Returns the instance for chaining.