javascript factorial

function factorial(n) {
  if (n < 0) return;
  if (n < 2) return 1;
  return n * factorial(n - 1);
}

// Simple arrow function solution
var factorial = n => (n <= 0) ? 1: 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);

function factorialize(num) {
  if(num < 2) return 1;
  return num *= factorialize(num - 1);
}

num = 5
factorialn = 1
function factorial() {
    for (i = 1; i <= num; i++) {
        factorialn *= i
    }
}
factorial()
console.log(factorialn)