Quicksort on 1.000.000 random elements within 0 – 1.000.000 range

quicksort.js

/**
 * Quicksort implementation by Nicholas C. Zakas
 * http://www.nczonline.net/blog/2012/11/27/computer-science-in-javascript-quicksort/
 */

var items = [];

for (var i = 0; i < 1000000; i++) {
    items.push(Math.round(Math.random() * 1000000));
}

function swap(items, firstIndex, secondIndex){
    var temp = items[firstIndex];
    items[firstIndex] = items[secondIndex];
    items[secondIndex] = temp;
}

function partition(items, left, right) {
    var pivot = items[Math.floor((right + left) / 2)];
    var i = left;
    var j = right;

    while (i <= j) {
        while (items[i] < pivot) {
            i++;
        }

        while (items[j] > pivot) {
            j--;
        }

        if (i <= j) {
            swap(items, i, j);
            i++;
            j--;
        }
    }

    return i;
}

function quickSort(items, left, right) {
    var index;

    if (items.length > 1) {
        left = typeof left != "number" ? 0 : left;
        right = typeof right != "number" ? items.length - 1 : right;

        index = partition(items, left, right);

        if (left < index - 1) {
            quickSort(items, left, index - 1);
        }

        if (index < right) {
            quickSort(items, index, right);
        }
    }

    return items;
}

var start = performance.now();
var results = quickSort(items);

console.log('Time:', performance.now() - start);
console.log('Results:', results.slice(-10).reverse())