Package Exports

event-emitter-object
event-emitter-object/source

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Readme

Javascript Event Emitter Object

A simple event emitter object that you can plug into your javascript libraries.

API is very similar to the node.js events.

Install

npm install event-emitter-object

Import

The default file imported by the module is polyfilled, bundled dist/index.js file:

const EventEmitter = require('event-emitter-object')

If you already have a compiler like babel or already polyfilling your codebase, using ./source/index.js recommended.

const EventEmitter = require('event-emitter-object/source')

Use

Let's say you have a state manager object to control the state of your app.

function StateManager() {}
StateManager.prototype.updateState = function updateState(payload) {
  // update state
  // ...
  // and inform listeners that the state has just updated
  this.emit('update')
}
module.exports = StateManager

To plug event emitter into your state manager:

StateManager.prototype = Object.assign({}, StateManager.prototype, EventEmitter.prototype)

Now, you can listen and emit events within your state manager:

const state = new StateManager()
state.on('update', function() {
  console.log('State updated!')
})

API

on(eventName, callback, opts)

Registers a new listener for a certain event.

emitter.on('someEvent', function() {
  console.log('Some event happened in some emitter.')
}, {
  once: true // default is false
})

once(eventName, callback)

This is a shortcut for the on method with {once: true}:

// instead of doin this:
emitter.on('someEvent', function(){}, {once: true})
// you can do this:
emitter.once('someEvent', function(){})

emit(eventName, args)

Emits a certain event with arguments.

emitter.emit('someEvent')

// or with arguments
emitter.on('anotherEvent', function(arg1, arg2) {
  console.log('Another event emitted with arguments: ', arg1, arg2)
})
emitter.emit('anotherEvent', ['hello', 'world'])

removeListeners(eventName)

Removes all listeners that belong to a certain event.

emitter.removeListeners('someEvent')

flush()

Removes all events and listeners.

emitter.flush()