Factorial Factory

[RazvanBugoi]

https://www.codewars.com/kata/528e95af53dcdb40b5000171/train/javascript

[RazvanBugoi]

function factorial (n) {
  let result = 1
  let initialNumber = n;
  if (n < 0) { return null }
  if (n = 0 ) { return 1 }

    while (initialNumber) {
      result *= initialNumber
      initialNumber--
    }

  return result
}