move duplicate items next to each other

sort.js

function sort(a) {
	var n = a.length;
	for (var j = 0; j < n - 2; j++) {
		for (var i = j + 1; i < n; i++) {
			if (a[i] == a[j]) {
				//swap
				if (a[i] != a[j + 1]) {
					var tmp = a[j + 1];
					a[j + 1] = a[i];
					a[i] = tmp;
				}
				j++;
			}
		}
	}
	return a;
}