1281. Subtract the Product and Sum of Digits of an Integer

Given an integer number n, return the difference between the product of its digits and the sum of its digits.

• Example 1:
  Input: n = 234
  Output: 15
  Explanation:
  Product of digits = 2 * 3 * 4 = 24
  Sum of digits = 2 + 3 + 4 = 9
  Result = 24 - 9 = 15

• Example 2:
  Input: n = 4421
  Output: 21
  Explanation:
  Product of digits = 4 * 4 * 2 * 1 = 32
  Sum of digits = 4 + 4 + 2 + 1 = 11
  Result = 32 - 11 = 21

var subtractProductAndSum = function(n) {
    let p = 1, s = 0;
    for(let i = 0; i < String(n).length; i++) {
        let value = Number(string(n)[i]); // Number(String(n).charAt(i))
        p *= value;
        s += value;
    }    
    return (p - s)
};