編寫程序使用遞歸，for，while計算數列1!+2!+3!+4!+5!+6!+7!+8!+9!+10!+...前N相的和

js方法：
遞歸：

function factorial( n ){ 
    return ( n <= 1 ) ? 1 : n * factorial( n-1 );
}
function getSum(n){
    sum=0;
    for(i=1;i<=n;i++){
        sum+=factorial(i);
    }
    return sum;
}

while

let factorial = n => {
        let product = 1;
        while (n) {
            product *= n;
            n--;
        }
        return product;
    };

    let getSum = n => {
        let sum = 0;
        while (n) {
            sum += factorial(n);
            n--;
        }
        return sum;
    }

for

function getSum(n){
        var product=1;sum=0;
        for(i=1;i<=n;i++){
            product*=i;
            sum+=product;
        }
        return sum
}