large-factorials.js

const factorial = n => {
  if (!n) return '1'
  let i, next, carret;
  const result = n.toString().split``.reverse().map(Number);

  while (--n) {
    i = carret = 0;
    while ((next = result[i++]) !== undefined || carret) {
      carret += n * (next || 0);
      result[i - 1] = carret % 10;
      carret = parseInt(carret / 10);
    }
  }

  return result.reverse().join``;
}
//https://www.codewars.com/kata/large-factorials/javascript

thankyou