Emitter

简体中文 | English

A small event emitter library.

Usage

import Emitter from 'small-emitter'
const emitter = new Emitter();

// subscribe to events
emitter.on('foo', function (p1, p2, p3) {
 // ...
});

// subscribe the event only once
emitter.once('foo', function (p1, p2, p3) {
 // ...
});

// publish events
emitter.emit('foo', 'p1', 'p2', 'p3');

// clearing all events
emitter.clear()

// use reference functions
function fn() {}
emitter.on('foo', fn)
emitter.off('foo', fn)

API

on(name: string, callback: () => void)

• Arguments

  • name name of the event
  • callback event's callback function

• Example

  const emitter = new Emitter()
  
  emitter.on('foo', (data) => {
    console.log(data)
  })
  
  emitter.emit('foo', 1) // 1
  emitter.emit('foo', 2) // 2
  

once(name: string, callback: () => void)

• Arguments

  • name name of the event
  • callback event's callback function

• Example

  const emitter = new Emitter()
  
  emitter.once('foo', (data) => {
    // The function will only be executed once
    console.log(data)
  })
  
  emitter.emit('foo', 'a') // 'a'
  emitter.emit('foo', 'b') // Not output
  

emit(name: string, ...args: any[])

• Arguments

  • name name of the event
  • ...args (optional) parameters passed in by the execution event

• Example

  const emitter = new Emitter()
  
  emitter.once('bar', (message, name) => {
    console.log(`${message}, ${name}`)
  })
  
  emitter.emit('bar', 'hi', 'Jack') // hi, Jack
  

off(name: string, callback?: () => void)

• Arguments

  • name name of the event
  • callback (optional) functions that need to be cleared or function reference

• Example

  const emitter = new Emitter()
  
  const fn = (message) => {
    console.log(message)
  }
  
  emitter.on('bar', fn)
  emitter.emit('bar', 'hi') // hi
  emitter.off('bar', fn)
  emitter.emit('bar', 'Jack') // Not output
  

clear()

• Calling this method will clear all events

• Example

  const emitter = new Emitter()
  
  emitter.on('foo', (value) => {
    console.log(value)
  })
  
  emitter.on('bar', (value) => {
    console.log(value)
  })
  
  emitter.emit('foo', 'hi, foo')
  emitter.emit('bar', 'hi, bar') // hi, bar
  emitter.clear()
  emitter.emit('foo', 'hi, Jack') // Not output
  emitter.emit('bar', 'hi, Tom') // Not output
  

License

MIT License