Pub sub example

var EventBus = {
  events: {},

  subscribe: function(event, listener) {
    // create the event if not yet created
    if(!this.events[event]) this.events[event] = [];

    // add the listener
    this.events[event].push(listener);
  },

  publish: function(event, data) {
    // return if the event doesn't exist, or there are no listeners
    if(!this.events[event] || this.events[event].length < 1) return;

    // send the event to all listeners
    this.events[event].forEach(function(listener) {
      listener(data || {});
    });
  }
};

EventBus.subscribe('foo', alert);
EventBus.publish('foo', 'Hello World!');

// source http://dev.housetrip.com/2014/09/15/decoupling-javascript-apps-using-pub-sub-pattern/