quick sort

quickSort.js

function quickSort(arr) {
    if (arr.length <= 1) {
        return arr;
    }
    var mid = [arr[0]];
    var left = [];
    var right = [];
    for (var i = 1; i < arr.length; i++) {
        if (arr[i] <= mid[0]) {
            left.push(arr[i]);
        } else {
            right.push(arr[i]);
        }
    }
    return quickSort(left).concat(mid, quickSort(right));
}