JS binary search

binary_search.js

var binarySearch = function (a, x) {
	var low = 0,
		high = a.length - 1,
		mid;

	while (low <= high) {
		mid = Math.floor((low + high) / 2);		

		if (a[mid] < x)
			low = mid + 1;
		else if (a[mid] > x)
			high = mid - 1;
		else
			return "found " + x + " at [" + mid + "]";
  	}

	return -1;	
};