Ovservable for JavaScript Classes

Observable.js

/**
 * To class Observable
 *
 */
function Observable() {}

Observable.prototype = {

  /**
   *
   */
  initEvents : function(listeners) {
    this.events = {};

    listeners = listeners || {};
    for (action in listeners) {
      if (typeof(listeners[action]) == 'function' || listeners[action] instanceof Function){
        this.on(action, listeners[action]);
      } else {
        this.on(action, listeners[action].fn, listeners[action].scope);
      }
    }
  },

  /**
   * Fire event
   */
  fireEvent : function(eventName/*,  _opt event data */) {
    var args = Array.prototype.slice.call(arguments);
    var eventName = args.shift();
    var fns = this.events[eventName];
    if (fns) {
      fns.forEach(function(f) {
        f.fn.apply(f.scope, args);
      });
    }
  },


  /**
   * Add event listener
   */
  on : function(eventName, fn, scope) {
    eventName = eventName.toLowerCase();
    if (!this.events[eventName]) {
      this.events[eventName] = [];
    }

    var fns = this.events[eventName];
    fns.push({
      fn : fn, scope : scope
    });
  },

  /**
   * Remove event listener
   */
  un : function(eventName, fn, scope) {
    eventName = eventName.toLowerCase();
    var fns = this.events[eventName];
    if (fns) {
      for (var i=0; i<fns.length; i++) {
        if (fns[i].fn == fn && fns[i].scope == scope) {
          fns.splice(i, 1);
          return true;
        }
      }
    }
    return false;
  },

  /**
   * Remove all event listeners
   */
  purgeListeners : function() {
    this.events = {};
  }

}