javascript3种方式创建函数及递归函数正确写法

function fun1(){}
var fun2=function(){};
var fun3=new Function('x','return x;');

 

function fact(number){
		if(number<=1){
			return 1;
		}else{
			return number*arguments.callee(number-1);//return number*fact(number-1);
		}
	}
var fact2=fact;
fact=null;
alert(fact2(5));