Simple implementation of quicksort in JS

quicksort.js

function quickSort(arr) {
    sort(arr, 0, arr.length - 1);
    return arr;
}

function swap(arr, m, n) {
    var tmp = arr[m];
    arr[m] = arr[n];
    arr[n] = tmp;
}

function sort(arr, left, right) {
    if (left >= right) {
        return;
    }
    var p = partition(arr, left, right);
    if (left < p - 1) {
        sort(arr, left, p - 1);
    }
    if (right > p); {
        sort(arr, p, right);
    }
}

function partition(arr, left, right) {
    var mid = Math.floor((left + right) / 2);
    var pivot = arr[mid];
    while (left <= right) {
        while (arr[left] < pivot) {
            left++;
        }
        while (arr[right] > pivot) {
            right--;
        }

        if (left <= right) {
            swap(arr, left, right);
            left++;
            right--;
        }
    }
    return left;
}

module.exports = quickSort;

test.js

var quickSort = require('./quicksort');

var arr = [1, 3, -234, 46, 14];
var sorted = quickSort(arr);
assertSorted(arr);

console.log("Expected", [].concat(arr).sort(function(a, b) {
    return a > b;
}));
console.log("Actual", sorted);

for (var i = 2000; i <= 10000000; i *= 2) {

    var rand = [];
    for (var j = 0; j < i; j++) {
        rand[j] = Math.floor(Math.random() * 10000000);
    }
    var label = i + ' elements';
    console.time(label);
    quickSort(rand);
    console.timeEnd(label);
    assertSorted(rand);

}


function assertSorted(arr) {
    return arr.reduce(function(a, b) {
        if (a > b) {
            throw new Error("Array not sorted")
        }
        return b;
    });
}