agent-skills/skills/vueuse-functions/references/useEventBus.md

category

category
Utilities

useEventBus

A basic event bus.

Usage

import { useEventBus } from '@vueuse/core'

const bus = useEventBus<string>('news')

function listener(event: string) {
  console.log(`news: ${event}`)
}

// listen to an event
const unsubscribe = bus.on(listener)

// fire an event
bus.emit('The Tokyo Olympics has begun')

// unregister the listener
unsubscribe()
// or
bus.off(listener)

// clearing all listeners
bus.reset()

Listeners registered inside of components setup will be unregistered automatically when the component gets unmounted.

TypeScript

Using EventBusKey is the key to bind the event type to the key, similar to Vue's InjectionKey util.

// fooKey.ts
import type { EventBusKey } from '@vueuse/core'

export const fooKey: EventBusKey<{ name: foo }> = Symbol('symbol-key')

import { useEventBus } from '@vueuse/core'

import { fooKey } from './fooKey'

const bus = useEventBus(fooKey)

bus.on((e) => {
  // `e` will be `{ name: foo }`
})

Type Declarations

export type EventBusListener<T = unknown, P = any> = (
  event: T,
  payload?: P,
) => void
export type EventBusEvents<T, P = any> = Set<EventBusListener<T, P>>
export interface EventBusKey<T> extends Symbol {}
export type EventBusIdentifier<T = unknown> = EventBusKey<T> | string | number
export interface UseEventBusReturn<T, P> {
  /**
   * Subscribe to an event. When calling emit, the listeners will execute.
   * @param listener watch listener.
   * @returns a stop function to remove the current callback.
   */
  on: (listener: EventBusListener<T, P>) => Fn
  /**
   * Similar to `on`, but only fires once
   * @param listener watch listener.
   * @returns a stop function to remove the current callback.
   */
  once: (listener: EventBusListener<T, P>) => Fn
  /**
   * Emit an event, the corresponding event listeners will execute.
   * @param event data sent.
   */
  emit: (event?: T, payload?: P) => void
  /**
   * Remove the corresponding listener.
   * @param listener watch listener.
   */
  off: (listener: EventBusListener<T>) => void
  /**
   * Clear all events
   */
  reset: () => void
}
export declare function useEventBus<T = unknown, P = any>(
  key: EventBusIdentifier<T>,
): UseEventBusReturn<T, P>