Class Emitter<T>

constructor

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

  Type Parameters

  • T extends Events

  Returns Emitter<T>

Readonly_listeners

emit

• emit<K extends string | number | symbol>(name: K, ...values: T[K]): void

  Triggers an event, calling all registered listeners with the provided value. Errors in listeners are caught and logged without interrupting other listeners. Listeners are snapshotted first (like Node's EventEmitter): a listener added during the emit runs from the next emit, so a once handler that re-registers itself cannot re-fire within the same emit.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    The event name to emit

  • ...values: T[K]

    The payload to pass to listeners

  Returns void

eventNames

• eventNames(): (keyof T)[]

  Lists all event names with active listeners.

  Returns (keyof T)[]

  Array of event names

eventually

• eventually<K extends string | number | symbol>(
      name: K,
      options?: number | WaitOptions,
  ): Promise<T[K]>

  Creates a promise that resolves when the specified event is emitted.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    Event name to wait for

  • options: number | WaitOptions = ...

    Timeout in milliseconds, or { timeout, signal }; aborting the signal removes the listener and timer and rejects with signal.reason

  Returns Promise<T[K]>

  Promise that resolves with the event payload when emitted

eventuallyIf

• eventuallyIf<K extends string | number | symbol>(
      name: K,
      predicate: Predicate<T[K]>,
      options?: number | WaitOptions,
  ): Promise<T[K]>

  Creates a promise that resolves when an event matching the predicate is emitted.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    Event name to wait for

  • predicate: Predicate<T[K]>

    Function that evaluates if the event payload should resolve the promise

  • options: number | WaitOptions = ...

    Timeout in milliseconds, or { timeout, signal }; aborting the signal removes the listener and timer and rejects with signal.reason

  Returns Promise<T[K]>

  Promise that resolves with the event payload when predicate matches

hasListener

• hasListener<K extends string | number | symbol>(
      name?: K,
      listener?: Listener<T[K]>,
  ): boolean

  Checks if an event has any listeners registered.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • Optionalname: K

    Optional event name to check

  • Optionallistener: Listener<T[K]>

    Optional listener to check

  Returns boolean

  true if the event has listener(s), false otherwise.

listeners

• listeners<K extends string | number | symbol>(
      name: K,
  ): Set<Listener<T[K]>> | undefined

  Gets all listeners for a given event name.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    The event name to get listeners for

  Returns Set<Listener<T[K]>> | undefined

  Set of listeners or undefined if none exist

off

• off<K extends string | number | symbol>(
      maybeName?: K,
      maybeListener?: Listener<T[K]>,
  ): number

  Removes one or more event listeners.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • OptionalmaybeName: K

    Optional event name. If not provided, removes all listeners for all events.

  • OptionalmaybeListener: Listener<T[K]>

    Optional listener to remove. If not provided but name is, removes all listeners for that event.

  Returns number

  Number of listeners removed

on

• on<K extends string | number | symbol>(
      name: K,
      listener: Listener<T[K]>,
  ): () => number

  Registers a new event listener.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    Event name to listen for

  • listener: Listener<T[K]>

    Function to call when event is emitted

  Returns () => number

  Unregister function that removes this listener when called

  Throws

  Error if the listener is already registered for this event

once

• once<K extends string | number | symbol>(
      name: K,
      listener: Listener<T[K]>,
  ): () => number

  Registers a listener that will be called exactly once when the event is emitted.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    Event name to listen for

  • listener: Listener<T[K]>

    Function to call when event is emitted

  Returns () => number

  Unregister function to remove the listener before it's triggered

onceIf

• onceIf<K extends string | number | symbol>(
      name: K,
      predicate: Predicate<T[K]>,
      listener: Listener<T[K]>,
  ): () => number

  Registers a listener that will be called once when an event matching the predicate is emitted.

  Type Parameters

  • K extends string | number | symbol

  Parameters

  • name: K

    Event name to listen for

  • predicate: Predicate<T[K]>

    Function that evaluates if the event payload should trigger the listener

  • listener: Listener<T[K]>

    Function to call when an event passes the predicate

  Returns () => number

  Unregister function to remove the listener before it's triggered