Javascript MergeSort

mergesort.js

// A simple JS mergesort, per Wikipedia's pseudocode
// http://en.wikipedia.org/wiki/Mergesort
// by K.R. Hale

var mergeSort = function(array) {
	//base case
	if (array.length <= 1) return array;

	//recursive case
	var middle = Math.floor(array.length / 2);
	var left = array.slice(0, middle);
	var right = array.slice(middle, array.length);

	return merge(mergeSort(left), mergeSort(right));
};

var merge = function(left, right) {
	var result = [];

	while (left.length && right.length) {
		if (left[0] <= right[0]) result.push(left.shift());
		else result.push(right.shift());
	}		
	
	while (left.length) result.push(left.shift());
	while (right.length) result.push(right.shift());

	return result;
};