Question

用javascript怎么求1到9 的阶乘的和

Answer 1

1到9 的阶乘的和?
是指1的阶乘 + 2的阶乘 + .... +9的阶乘吗?
<script language="javascript">
var sum = 0; //1-9阶层总和
for(i=1;i<=9;i++){
var k = 1;
for(j=1;j<=i;j++){
k = k * j;
}
sum = sum + k;
document.write(i+' 的阶层 '+(i==9?'=':'+'));
}
document.write('结果:'+sum);
</script>

Answer 2

var fn = function(a){
var end = 1;
for (var i = a; i>1; i--){
end *= i;
}
return end;
}
var ans = function(a,b){
var sum = 0;
for (var i=a;i<=b;i++){
sum += fn(i);
}
return sum;
}
alert(ans(1,9));//计算1到9的阶