关于javascript的简单问题，请高手帮帮忙

<script>
i=1;
j=1;
k=0;
function aa(x)
{
for(i=1;i<=x;i++)
{
j=j*i;
k=k+j;
}
return k;
}
alert(aa(5))
</script>

var i=1,j=(1,2,3,4,5);
while (j>=1)
{
i=i*j;
j--;
}
document.write(i);

递归 应该很清楚
<var Vactorial = function()
{
var obj = new Object();
obj.total = 1;
obj.start = function( r )
{
obj.total = obj.total * r;
if(r>1){
obj.start(r-1);}
return obj.total;
}
return obj;
}
var v = new Vactorial();
sum=0;
for (i=1;i<=5;i++)
{
sum=sum+v.start(i);
}
alert(sum);