code: function(event) {
  		event = event || window.event;
  		self.state = count++ ? "change" : "start";
  		self.wheelDelta = event.detail ? event.detail * -20 : event.wheelDelta;
  		conf.listener(event, self);
  		clearTimeout(interval);
  		interval = setTimeout(function() {
  			count = 0;
  			self.state = "end";
  			self.wheelDelta = 0;
  			conf.listener(event, self);
  		}, timeout);
  	}
docs: Tracking the events.