factorial function javascript

function factorial(n) {
  if (n < 0) return;
  if (n < 2) return 1;
  return n * factorial(n - 1);
}function factorialize(num) {
  if (num === 0 || num === 1)
    return 1;
  for (var i = num - 1; i >= 1; i--) {
    num *= i;
  }
  return num;
}
factorialize(5);// Simple arrow function solution
var factorial = n => (n <= 0) ? 1: n * factorial(n - 1);    function factorial(n) {
        if (n > 1) {
            return n * factorial(n - 1);
        }
        return 1;
    }