Nodejs Array Merge Sort mergeSort(sortKey, direction)

Method Source Code

Array.prototype.mergeSort = function(sortKey, direction){
  var unsortedArray = this;
  if(unsortedArray.length < 2) return unsortedArray;

  var middle = Math.floor(unsortedArray.length/2);
  var leftSubArray = unsortedArray.slice(0,middle).mergeSort(sortKey, direction);
  var rightSubArray = unsortedArray.slice(middle).mergeSort(sortKey, direction);

  var sortedArray = merge(leftSubArray, rightSubArray);
  return sortedArray;

  function merge(left, right) {
    var combined = [];
    while(left.length>0 && right.length>0){
      var leftValue = (sortKey ? left[0][sortKey] : left[0]);
      var rightValue = (sortKey ? right[0][sortKey] : right[0]);
      combined.push((direction === 'desc' ? leftValue > rightValue : leftValue < rightValue) ? left.shift() : right.shift())
    }/*  www .  j  a  v a  2s .co m*/
    return combined.concat(left.length ? left : right)
  }
}

Related

1. mergeSort()

   Array.prototype.mergeSort = function () {
     if ( this.length < 2 ) {
       return this;
     var mid_idx = Math.floor( this.length / 2 )
     var left = this.slice(0,mid_idx).mergeSort();
     var right = this.slice(mid_idx).mergeSort();
     return merge(left, right);
   function merge(left, right) {
     var result = [];
       while (left.length > 0 && right.length > 0) {
         var nextItem = (left[0] < right[0]) ? left.shift() : right.shift();
         result.push(nextItem);
     return result.concat(left).concat(right);
   console.log();
   console.log( JSON.stringify( [].mergeSort() ) == JSON.stringify( [] )  );
   console.log( JSON.stringify( [6,5,3,1,8,7,2,4].mergeSort() ) == JSON.stringify( [1,2,3,4,5,6,7,8] ) );
   console.log();
   

2. mergeSort()

   ;"use strict";
   var log=function(msg){console.log(msg);};
   var alert=function(msg){log(msg);};
   var arr = [3,6,7,5,3,6,2,9,1,5,33,-12,0,-122,-Infinity, 125, 33, 55, 77];
   Array.prototype.mergeSort = function () {
     function _merge(arrLeft, arrRight){
         var result = [],
         leftIdx = 0,
         rightIdx = 0;
   ...
   

3. mergeSort()

   Array.prototype.mergeSort = function() {
       function sort(array) {
           var length = array.length,
               mid    = Math.floor(length * 0.5),
               left   = array.slice(0, mid),
               right  = array.slice(mid, length);
           if(length === 1) {
             return array;
           return merge(sort(left), sort(right));
       function merge(left, right) {
           var result = []
           for (var li=0,ri=0,i=0;i<left.length+right.length;i++){
               if (li < left.length && ri < right.length) {
                   if (less(left[li], right[ri])) {
                       result[i]=left[li]
                       li++
                       continue
                   else {
                       result[i]=right[ri]
                       ri++
                       continue
               if (li===left.length) {
                   result[i]=right[ri]
                   ri++
                   continue
               else {
                   result[i]=left[li]
                   li++
                   continue
           virtualize(result, 0)
           return result
       var newArray=sort(this)
       return newArray
   

4. mergeSort()

   Array.prototype.mergeSort = function() {
       function sort(array) {
           var length = array.length,
               mid    = Math.floor(length * 0.5),
               left   = array.slice(0, mid),
               right  = array.slice(mid, length);
           if(length === 1) {
             return array;
           return merge(sort(left), sort(right));
       function merge(left, right) {
           var result = []
           for (var li=0,ri=0,i=0;i<left.length+right.length;i++){
               if (li < left.length && ri < right.length) {
                   if (less(left[li], right[ri])) {
                       result[i]=left[li]
                       li++
                       continue
                   else {
                       result[i]=right[ri]
                       ri++
                       continue
               if (li===left.length) {
                   result[i]=right[ri]
                   ri++
                   continue
               else {
                   result[i]=left[li]
                   li++
                   continue
           return result
       var newArray=sort(this)
       return newArray
   

5. mergeSort(arr2, arr3)

   Array.prototype.mergeSort = function(arr2, arr3) {
     return this.merge2way(arr2.merge2way(arr3));
   var maxNumber = process.argv[2];
   function getRandomArbitrary(min, max) {
     return Math.round(Math.random() * (max - min) + min);
   var arr1 = [getRandomArbitrary(1, 5)],
     arr2 = [getRandomArbitrary(1, 5)],
   ...