The factorial of JavaScript recursion

Factorial, that is, 5! = 5*4*3*2*1, first look at the traditional approach, using the while loop implementation:

function factorial (num) {  var result = num;  if (num<0) {    return-1;    Negative returns-1  }  if (num = = 0) {    return 1;    0 factorial is 1  }    while (num-->2) {    result = Result*num;      }  return result;}

The JavaScript recursive function calls itself through it, using recursion, the idea of factorial should be factorial (num) *factorial (num-1) *factorial (num-2) ... factorial (0), That is, each time the num-1 is called itself as a parameter:

function Factorial2 (num) {  if (num <0) {    return-1;  }  if (num = = 0) {    return 1;  }  Return num* (Factorial2 (num-1));}

　　

The factorial of JavaScript recursion