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1.1.7 • Public • Published

events-ex Build Status npm downloads license

Browser-friendly enhanced events most compatible with standard node.js and coffee-script. It's modified from event-emitter mainly. It can add event-able to your class directly.


  • more powerful event-able ability
  • hookable event system


  • Difference with node events
    • domain is not supported yet(TODO)
    • broken change: The event object bubbling Supports
      • the event object as listener's "this" object.
      • return the result property of event object to emitter.
      • prevent the rest of listener from be excuted if set the stopped property of event object to true
      • broken change: the emit return the result of listeners's callback function instead of the successful state.
      • broken change: the this object of listeners' callback function is the Event Object instead of the emitter object.
        • the emitter object is put into the target property of the Event Object.
  • Difference with event-emitter
    • broken change: The event object bubbling Supports(see above)
    • add the defaultMaxListeners class property to keep compatible with node events.
    • add the setMaxListeners method to keep compatible with node events.
    • add error, newListener and removeListener events to keep compatible with node events.
    • add listeners() method to keep compatible with node events.
    • add listenerCount() class method to keep compatible with node events.


$ npm install events-ex

To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: Browserify, Webmake or Webpack


Add the event-able feature to your class directly:

eventable = require('events-ex/eventable')
class MyClass
  # advanced usage see API topic. 
  eventable MyClass
my = new MyClass
my.on 'event'->
  console.log 'event occur'
  # be care: @(this) is the event object. not the `my` instance. 
  # the my instance is @target. 
my.emit 'event'

the following is javascript:

var eventable = require('events-ex/eventable');
function MyClass() {}
var my = new MyClass;
my.on('event', function() {
  console.log('event occur');

Node JS events Usage:

## Coffee-script demo bubbling usage: 
EventEmitter = require('events-ex')
inherits     = require('inherits-ex')
ABORT = -1
DONE = 0
class MyDb
  inherits MyDbEventEmitter
  get: (key)->
    # Demo the event object bubbling usage: 
    result = @emit 'getting'key
    if isObject result
      return if result.state is ABORT
      return result.result if result.state is DONE
db = new MyDb
db.on 'getting'(key)->
  result = myGet(key);
  if result?
    # get the key succ 
    this.result =
      state: DONE
      result: result
  else if result is null
    # abort default get key. 
    this.result = state: ABORT;
    # this.stopped = true # it will skip other listeners if true 
// js demo bubbling usage:
let EventEmitter = require('events-ex')
let isObject = require('util-ex/lib/is/type/object')
const ABORT = -1
const DONE = 0
class MyDb extends EventEmitter {
  get(key) {
    // Demo the event object bubbling usage:
    let result = this.emit('getting', key)
    if(isObject(result)) {
      if (result.state === ABORT) return
      if (result.state === DONE)  return result.result
    return _get(key)
let db = new MyDb
db.on('getting', function(key){
  result = myGet(key);
  if (result != null) {
    // get the key succ
    this.result = {
      state: DONE,
      result: result,
  } else if (result === null) {
    // abort default get key.
    this.result = {state: ABORT};
    // this.stopped = true // it will skip other listeners if true

event-emitter usage:

var ee = require('event-ex/event-emitter');
var MyClass = function () { /* .. */ };
ee(MyClass.prototype); // All instances of MyClass will expose event-emitter interface
var emitter = new MyClass(), listener;
emitter.on('test', listener = function (args) {
  // … react to 'test' event
emitter.once('test', function (args) {
  // … react to first 'test' event (invoked only once!)
emitter.emit('test', arg1, arg2/*…args*/); // Two above listeners invoked
emitter.emit('test', arg1, arg2/*…args*/); // Only first listener invoked'test', listener);              // Removed first listener
emitter.emit('test', arg1, arg2/*…args*/); // No listeners invoked


eventable(class[, options]) (events-ex/eventable)

Add the event-able ability to the class directly.

  • class: the class to be injected the ability.
  • options (object): optional options
    • include (string[]|string): only these emitter methods will be added to the class
      • NOTE: static method should use the prefix '@' with name.
    • exclude (string[]|string): theses emitter methods would not be added to the class
      • NOTE: static method should use the prefix '@' with name.
    • methods (object): hooked methods to the class
      • key: the method name to hook.
      • value: the new method function
        • use this.super() to call the original method.
        • this.self is the original this object.
    • classMethods (object): hooked class methods to the class
  eventable  = require('events-ex/eventable')
  #OtherClass = require('OtherClass') 
  class OtherClass
    exec: -> console.log "my original exec"
  class MyClass
    # only 'on', 'off', 'emit' and static methods 'listenerCount' added to the class 
    eventable MyClassinclude: ['on''off''emit''@listenerCount']
  # add the eventable ability to OtherClass and inject the exec method of OtherClass. 
  eventable OtherClassmethods:
    exec: ->
      console.log "new exec"
      @super() # call the original method 

allOff(obj) (events-ex/all-off)

keep compatible only: the removeAllListeners has already been buildin.

Removes all listeners from given event emitter object

hasListeners(obj[, name]) (events-ex/has-listeners)

Whether object has some listeners attached to the object. When name is provided, it checks listeners for specific event name

var emitter = ee();
var hasListeners = require('events-ex/has-listeners');
var listener = function () {};
hasListeners(emitter); // false
emitter.on('foo', listener);
hasListeners(emitter); // true
hasListeners(emitter, 'foo'); // true
hasListeners(emitter, 'bar'); // false'foo', listener);
hasListeners(emitter, 'foo'); // false

pipe(source, target[, emitMethodName]) (events-ex/pipe)

Pipes all events from source emitter onto target emitter (all events from source emitter will be emitted also on target emitter, but not other way). Returns pipe object which exposes pipe.close function. Invoke it to close configured pipe. It works internally by redefinition of emit method, if in your interface this method is referenced differently, provide its name (or symbol) with third argument.

unify(emitter1, emitter2) (events-ex/unify)

Unifies event handling for two objects. Events emitted on emitter1 would be also emitter on emitter2, and other way back. Non reversible.

var eeUnify = require('events-ex/unify');
var emitter1 = ee(), listener1, listener3;
var emitter2 = ee(), listener2, listener4;
emitter1.on('test', listener1 = function () { });
emitter2.on('test', listener2 = function () { });
emitter1.emit('test'); // Invoked listener1
emitter2.emit('test'); // Invoked listener2
var unify = eeUnify(emitter1, emitter2);
emitter1.emit('test'); // Invoked listener1 and listener2
emitter2.emit('test'); // Invoked listener1 and listener2
emitter1.on('test', listener3 = function () { });
emitter2.on('test', listener4 = function () { });
emitter1.emit('test'); // Invoked listener1, listener2, listener3 and listener4
emitter2.emit('test'); // Invoked listener1, listener2, listener3 and listener4


npm i events-ex

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