ngEventEmitter

This is a small library to add an event emitter functionality in AngularJS 1.x, and it contains a small factory with two methods, .on and .triggerEvent, written mostly because I didn't want to depend to the $rootScope or the $scope providers, but to have a much more lightweight version of event emitters.

Installation

To download the library you can do it via bower:

bower install ng-event-emitter --save

Or via NPM

npm install ng-event-emitter --save

To add to your angular project, just add the ngEventEmitter into your module dependencies, and EventEmitter as a dependency injection to your service/controller.

The .on(eventName, callback) method requires two arguments, an eventName (a simple string to identify the event) and a callback function. Multiple callbacks can be attached to the same event, and they will all be invoked once the event is triggered. The .triggerEvent(eventName [,data]) method simply trigger the passed event, which is the only compulsory argument, a second argument can be passed to send data to the .on method, as shown in the second example down below.

angular.module('myApp', ['ngEventEmitter'])

.service('MyService', function(EventEmitter){
  this.events = new EventEmitter();

  this.events.on('salute', function(){
    console.log('hello world');
  });

  this.events.triggerEvent('salute'); // it will print `hello world` in the console

  // Passing data from the triggerEvent
  this.events.on('cheers', function(name){
    console.log('cheers ' + name);
  });

  this.events.triggerEvent('cheers', 'Alex'); // it will print `cheers Alex` in the console

  // Multiple callbacks for the same event

  this.events.on('test', function(){
    console.log('test 1');
  });

  this.events.on('test', function(){
    console.log('test 2');
  });

  this.events.triggerEvent('test'); // it will print `test 1` and `test 2` in the console

  // One callback for multiple events with passed data

  this.events.on(['test1', 'test2'], function(name){
    console.log('hello ' + name);
  });

  this.events.triggerEvent('test1', 'Alex'); // it will print `test Alex` in the console
  this.events.triggerEvent('test2', 'Liza'); // it will print `test Liza` in the console
});

If you want to clear all the callbacks previously assigned to a specific events, you can pass the options object as a second argument, specifying clearEvent to be true, as shown in the example below:

this.events.on('test', function(){
  console.log('test 1');
});

this.events.on('test', {clearEvent: true} function(){
  console.log('test 2');
});

this.events.triggerEvent('test'); // it will print `test 2` only in the console

Unit tests

To run the unit tests, just use the command npm test from the command line, but be sure to have ran npm install and bower install before to install all the dependencies needed.