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useEventBus ​

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Last Changed
5 months ago

A basic event bus.

Demo ​

News channel:
Television:
--- no signal ---

Usage ​

ts
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()
js
import { useEventBus } from '@vueuse/core'
const bus = useEventBus('news')
function listener(event) {
  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.

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

export const fooKey: EventBusKey<{ name: foo }> = Symbol('symbol-key')
js
export const fooKey = Symbol('symbol-key')
ts
import { useEventBus } from '@vueuse/core'

import { fooKey } from './fooKey'

const bus = useEventBus(fooKey)

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

Type Declarations ​

Show Type Declarations
typescript
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>

Source ​

Source • Demo • Docs

Contributors ​

Anthony Fu
TuiMao233
jahnli
丶远方
Haoqun Jiang
sun0day
webfansplz
Jairo Blatt

Changelog ​

v10.0.0-beta.0 on 3/14/2023
dd514 - fix(useEventBus,createEventHook)!: dedupe registration of the same function (#2748)
37ec7 - fix: use ts-ignore instead of ts-expect-error for version-specifc errors (#2802)

Released under the MIT License.