pubsub.js

function Pubsub() {
  this.events = {};

}

Pubsub.prototype.publish = function(event, args) {
  if (!this.events[event]) {
    return false;
  }
  var subscribers = this.events[event];
  var len = subscribers ? subscribers.length : 0;
  while (len--) {
    subscribers[len]();
  }
  return this;
}

Pubsub.prototype.subscribe = function(event, func) {
  if (!this.events[event]) {
    this.events[event] = [];
  }
  this.events[event].push(func);
}

Pubsub.prototype.unsubscribe = function(event, func) {
  var self = this;
  if (this.events[event]) {
    this.events[event].forEach(function(el, index){
      if (el == func) {
        self.events.splice(index, 1);
      }
    })
  }
}

var pubsub = new Pubsub();

var eat = function() {
  console.log("I am eating");
}

var drink = function() {
  console.log("I am drinking");
}
var running = function() {
  console.log("I am running");
}

pubsub.subscribe("dinner", eat);
pubsub.subscribe("dinner", drink);
pubsub.subscribe("sports", running);

pubsub.publish("dinner");
// should log
// I am drinking
// I am eating

pubsub.publish("sports")
// should log
// I am running