Calculating Fibonacci asynchronously

gistfile1.js

        var data = [0,1];
	
	function retrieveData(callback){
	   var x = data[data.length - 1];
	   var y = data[data.length - 2];
	   setTimeout(function(){
	     callback(x,y);
	   },0);
	}
	
	function calculateSum(x,y,callback){
	   var sum = x+y;
	   setTimeout(function(){
	      callback(sum);
	   },0);
	}
	
	function addSum(sum,callback){
	   data.push(sum);
	   setTimeout(callback,0);
	}
	
	//Adds count fibonnacci elementd to data
	function fibonacci(count){
	   var i;
	   for (i=0; i<count; i++){
	      retrieveData(function(x,y){
	         calculateSum(x,y,function(sum){
		    addSum(sum,function(){
		       console.log(data);
		    });
		 });
	      })
	   }
	}