Greatest Common Divisor in JavaScript

gcd.js

/*
 * Uses the Euvlidean Algorithm.
 * http://en.wikipedia.org/wiki/Euclidean_algorithm
 */
function greatestCommonDivisor( a, b ) {
  if ( b > a ) {
    var t = a;
    a = b;
    b = t;
  }

  var difference = a - b;
  
  if ( difference == 0 ) {
    return a;
  } else return greatestCommonDivisor( difference, b );
}