recursion.js

/*exercize from http://eloquentjavascript.net/03_functions.html#p_Yv2DEaMWee
We’ve seen that % (the remainder operator) can be used to test whether a number is even or odd by using % 2 to check whether it’s divisible by two. 
Here’s another way to define whether a positive whole number is even or odd:
	Zero is even.
	One is odd.
	For any other number N, its evenness is the same as N - 2.
Define a recursive function isEven corresponding to this description. The function should accept a number parameter and return a Boolean.
Test it on 50 and 75. See how it behaves on -1. Why? Can you think of a way to fix this?*/

/*TRIES*/

function isEven(n) {
	if ((n-2) == 0)
		return true;
	else if ((n-2) == 1)
		return false;
	else 
		return n-2;
}






function isEven(n) {
  if (n == 0)
    return true;
  else if (n == 1)
    return false;
  else if (n < 0)
    return isEven(-n);
  else
    return isEven(n - 2);
}