http://www.freecodecamp.com/thetinybeaker 's solution for Bonfire: Factorialize a Number

bonfire-factorialize-a-number.js

// Bonfire: Factorialize a Number
// Author: @thetinybeaker
// Challenge: http://www.freecodecamp.com/challenges/bonfire-factorialize-a-number
// Learn to Code at Free Code Camp (www.freecodecamp.com)

// Return factorial of a given interger passed though the factorialize function.

function factorialize(num) {
  // if num (recursively gotten to value of 0, or starts out at 0) is 0, then the function returns 1.
  if (num === 0){
    return 1;
  }
  // if num (starts out) at below 0, function returns 1. num can never recursively arrive at below 0, since that possibility ends with num === 0 returning 1. 
  else if (num < 0){
    return -1;
  }
  // call stack. number is factorialized by calling the same function over and over again, with the new num value 1 smaller than previous num value.
  else {
    return (num * factorialize(num-1));
  }
  
}


factorialize(5);