14-数组求和之递归方式

for循环太过简单，不赘述

var arr = [2, 5, 6, 8, 6, 8, 7, 12, 1, 3, 4, 100];

function totalFn(arr) {
    let total = 0;
    let len = arr.length - 1;

    function fn(len) {
        total += arr[len];
        if (len === 0) return total;
        fn(len - 1);
    }
    fn(len);
    return total;
}

let res = totalFn(arr);
console.log(res);