factorial javascript function

function factorial(n) {
  if (n < 0) return;
  if (n < 2) return 1;
  return n * factorial(n - 1);
}function factorialize(num) {
  if(num < 2) return 1;
  return num *= factorialize(num - 1);
}    function factorial(n) {
        if (n > 1) {
            return n * factorial(n - 1);
        }
        return 1;
    }function factorialize(num) {
  var result = num;
  if (num === 0 || num === 1) 
    return 1; 
  while (num > 1) { 
    num--;
    result *= num;
  }
  return result;
}