MasterCardGenerator.js

const masterCardNumber = () => {
  (masterCardDigits = [5]), (masterCardDigSum = 1);
  var r = Math.floor(5 * Math.random() + 1);
  masterCardDigits.push(r), (masterCardDigSum += r);
  for (var a = 0; a < 13; a++)
    (r = Math.floor(10 * Math.random())),
      masterCardDigits.push(r),
      a % 2 == 0 && (r *= 2) > 9 && (r -= 9),
      (masterCardDigSum += r);
  var t = 10 - (masterCardDigSum % 10);
  return (masterCardDigSum % 10 == 0 && (t = 0),
  masterCardDigits.push(t),
  masterCardDigits).join("");
};

module.exports = masterCardNumber;