Nodejs Utililty Methods Array Quick Sort

Array.prototype.quickSort = function (comparator) {
  if (typeof comparator !== "function") {
    comparator = function (x, y) {
      if (x === y) {
        return 0;
      } else if (x < y) {
        return -1;
      } else {
        return 1;
...

Array.prototype.quickSort = function(start, len) {
  if (typeof len === "undefined") {
    len = this.length;
  if (len < 2) {
    return this;
};
Array.prototype.swap = function (idx1, idx2) {
...

Array.prototype.quick_sort = function () {
    if (this.length < 2) { return this; }
    var pivot = this[Math.round(this.length / 2)];
    return this.filter(x => x <  pivot)
               .quick_sort()
               .concat(this.filter(x => x == pivot))
               .concat(this.filter(x => x >  pivot).quick_sort());
};

Array.prototype.quick_sort = function () {
    if (this.length < 2) { return this; }
    var pivot = this[Math.round(this.length / 2)];
    return this.filter(x => x < pivot)
               .quick_sort()
               .concat(this.filter(x => x === pivot))
               .concat(this.filter(x => x > pivot).quick_sort());
};

Array.prototype.quick_sort = function ()
    if (this.length <= 1)
        return this;
    var pivot = this[Math.round(this.length / 2)];
    return this.filter(function (x) { return x <  pivot }).quick_sort().concat(
           this.filter(function (x) { return x == pivot })).concat(
           this.filter(function (x) { return x >  pivot }).quick_sort());

Array.prototype.quick_sort = function () {
    if (this.length < 2) { return this; }
    var pivot = this[Math.floor(Math.random() * this.length)];
    return this.filter(x => x <  pivot)
               .quick_sort()
               .concat(this.filter(x => x == pivot))
               .concat(this.filter(x => x >  pivot).quick_sort());
};

function partition(array, begin, end, pivot)
  var piv=array[pivot];
  array.swap(pivot, end-1);
  var store=begin;
  var ix;
  for(ix=begin; ix<end-1; ++ix) {
    if(array[ix]<=piv) {
      array.swap(store, ix);
...

Array.prototype.swap=function(a, b)
  var tmp=this[a];
  this[a]=this[b];
  this[b]=tmp;
function partition(array, begin, end, pivot)
  var piv=array[pivot];
...

$(function ($) {
function dosort(form)
  var array=form.unsorted.value.split(/ +/);
  quick_sort(array);
  form.sorted.value=array.join(' ');
function quick_sort(array)
  qsort(array, 0, array.length);
function qsort(array, begin, end)
  if(end-1>begin) {
    var pivot=begin+Math.floor(Math.random()*(end-begin));
    pivot=partition(array, begin, end, pivot);
    qsort(array, begin, pivot);
    qsort(array, pivot+1, end);
function partition(array, begin, end, pivot)
  var piv=array[pivot];
  array.swap(pivot, end-1);
  var store=begin;
  var ix;
  for(ix=begin; ix<end-1; ++ix) {
    if(array[ix]<=piv) {
      array.swap(store, ix);
      ++store;
  array.swap(end-1, store);
  return store;
Array.prototype.swap=function(a, b)
  var tmp=this[a];
  this[a]=this[b];
  this[b]=tmp;
});

Array.prototype.swap=function swapf(a, b)
    var tmp=this[a];
    this[a]=this[b];
    this[b]=tmp;
function partition(array, begin, end, pivot)
    var piv=array[pivot];
...