A simple event bus with disposable support.

Features

• Type-specific listeners (on/once) and global subscribers (subscribe)
• Returns IUnsubscribable for easy cleanup
• Implements IBatchDisposable for resource management
• Exception isolation: one handler's error won't stop other handlers
• Alias methods: off for removeListener, emit for dispatch
• listenerCount() to get the number of listeners

Install

• npm

  npm install --save @guanghechen/eventbus

• yarn

  yarn add @guanghechen/eventbus

Usage

import type { IEvent, IEventHandler } from '@guanghechen/eventbus'
import { EventBus } from '@guanghechen/eventbus'

enum EventTypes {
  INIT = 'INIT',
  EXIT = 'EXIT',
}

const eventBus = new EventBus<EventTypes>('my-bus')

const handle: IEventHandler<EventTypes> = (evt, eventBus): void => {
  console.log('evt:', evt)
}

// Listen for specific event, returns IUnsubscribable
const unsub1 = eventBus.on(EventTypes.INIT, handle)

// Listen for specific event, auto-removed after first call
const unsub2 = eventBus.once(EventTypes.INIT, handle)

// Subscribe to all events
const unsub3 = eventBus.subscribe(handle)

// Dispatch an event
eventBus.dispatch({ type: EventTypes.INIT, payload: { id: 1 } })
// Or use alias
eventBus.emit({ type: EventTypes.INIT, payload: { id: 1 } })

// Remove listener
eventBus.off(EventTypes.INIT, handle)
// Or use unsubscribable
unsub1.unsubscribe()

// Get listener count
console.log(eventBus.listenerCount()) // all listeners + subscribers
console.log(eventBus.listenerCount(EventTypes.INIT)) // only INIT listeners

// Cleanup all listeners and subscribers
eventBus.cleanup()

// Dispose the event bus (also disposes registered disposables)
eventBus.dispose()

API

EventBus<T>

| Method | Description | | ----------------------------------- | ----------------------------------------------------- | | on(type, handle) | Listen for a specific event type | | once(type, handle) | Listen for a specific event type, auto-removed | | off(type, handle) | Remove a listener (alias of removeListener) | | removeListener(type, handle) | Remove a listener | | subscribe(handle, once?) | Subscribe to all events | | unsubscribe(handle) | Cancel a subscription | | dispatch(evt) | Dispatch an event | | emit(evt) | Dispatch an event (alias of dispatch) | | listenerCount(type?) | Get listener count | | cleanup() | Remove all listeners and subscribers | | dispose() | Dispose the event bus | | registerDisposable(disposable) | Register a disposable to be disposed with the bus |

Reference

• homepage