State machine

gistfile1.js

(function(window, $){
  
  var StateMachine = function(){};
  StateMachine.fn  = StateMachine.prototype;
  $.extend(StateMachine.fn, {
    subscribe: $.subscribe,
    publish: $.publish
  });

  StateMachine.fn.add = function(controller){
    this.subscribe("change", function(e, current){
      if (controller == current)
        controller.activate();
      else
        controller.deactivate();
    });

    controller.active = $.proxy(function(){
      this.publish("change", controller);
    }, this);
  };

  window.StateMachine = StateMachine;
  
})(window, window.jQuery);