Since the first time I used it, many, many years ago, I loved recursion. Recursion is so powerful than can give you a stack overflow (hahaha... silly joke).

I was studying some algorithms when I saw this non-recursive-but-still-pretty-cool implementation of a GCD algorithm. GCD as you know calculates the gratest common divisor between two numbers. Piece of cake, but fun to play with :)

Here is the non recursive version:

7	function GCD( x, y) {
8	while(y>0) {
9	x = x%y;
10	x^=y;y^=x;x^=y; // XOR swap
11	}
12	return x;
13	}

And here is the recursive version:

23	function GCD(x,y) {
24	return (y==0)? x : GCD(y, x%y);
25	}

As I said, I love recursion, so I will pick the second version :)

You can test both of them on tide4javascript.com, which has a pretty good step-by-step javascript debugger, alongside with a lot of algorithms you may want to study :)