gistfile1.js

function uniq(sortedArray) {
    var output = [];
    sortedArray.reduce(function(previous, current) {
        if (current != previous) {
            output.push(current);
        }
        return current;
    }, null);
    return output;
}

var arr = ["z", "a", "b", "c", "a", "a", "b"];
arr.sort();
uniq(arr);
// => ["a", "b", "c", "z"]