Simple mechanism for randomizing the contents of an Array

array-shuffle.js

var shuffle = function(source) {
	var ret = Array.prototype.slice.call(source),
		len = source.length,
		i = len,
		rand, temp;
	
	while (i--) {
	 	rand = parseInt( Math.random() * len, 10 );
		temp = ret[ i ];
  		ret[ i ] = ret[ rand ];
  		ret[ rand ] = temp;
 	}
	
	return ret;
};

// Usage:
shuffle( ['a', 'b', 'c', 'd'] )