how does factorize works in javascript code example

Example 1: javascript factorial

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

Example 2: factorial program in javascript

function fact(N){
  if(N <= 1){
  	return "1";
  }
  else
  {
    return N * fact(N-1);  
  }
}

fact(5);