Basic Javascript PubSub Pattern

pubsub.js

//events - a super-basic Javascript (publish subscribe) pattern

var events = {
  events: {},
  on: function (eventName, fn) {
    this.events[eventName] = this.events[eventName] || [];
    this.events[eventName].push(fn);
  },
  off: function(eventName, fn) {
    if (this.events[eventName]) {
      for (var i = 0; i < this.events[eventName].length; i++) {
        if (this.events[eventName][i] === fn) {
          this.events[eventName].splice(i, 1);
          break;
        }
      };
    }
  },
  emit: function (eventName, data) {
    if (this.events[eventName]) {
      this.events[eventName].forEach(function(fn) {
        fn(data);
      });
    }
  }
};

Other objects should be able to call:

events.on("eventName", eventHandlerFunction) to subscribe to an event
events.off("eventName") to unsubscribe
events.emit("eventName", data) to trigger the event and notify all the listeners

emit can be renamed to trigger