Undo sort on sorted array in javascript -

i have following code:

//data_r array values  var = 0; var sort_order = new array();  data_r.sort(function (a,b) {     var res = a[0] - b[0];      sort_order[i] = res;     i++;      return res; }); 

in end, sort_order array contains actions performed when sorted items. if want sort second array same way first can following:

//data_x array values  var = 0; data_x.sort(function (a,b) {     i++;     return sort_order[i-1]; }); 

now data_x array sorted same way data_r array.

the question is, how can undo sort on data_r array?

the following code incorrect:

var unsort = new array();  for(var = 0; < data_r.length; i++)     unsort[i] = sort_order[i]*(-1);//-1 perfom oposite action 

why, please?

edit:

i can't make copy of array.

i have array #1. sort it.

then receive array #2 but array sorted based on array #1.

i need reverse sorting on array #2.

edit 2:

array #1 = {9, 5, 3, 0, 2}

i sort array #1:

array #1 = {0, 2, 3, 5, 9}

now receive array #2 sorted based on array #1:

array #2 = {"home", "car", "train", "pc", "mouse"}

i need make array #2 this:

array #2 = {"mouse, "pc", "train", "home", "car"}

solved: http://jsfiddle.net/fqm3a/

see @duskwuff's answer on why approach doesn't work.

instead, introduce mapping between original data , sorted data.

{0:2, 1:3, 2:1, 3:0} 

which means first element became third, second became last , on. below we'll use array instead of object.

why map help? can sort like dataset using indizes in pointers data you're going compare. , can apply mapping on other datasets. , can reverse mapping easily. see in code:

// data_r, data_x arrays values  var l = data_r.length; var sort_order = new array(l); (var i=0; i<l; i++) sort_order[i] = i; // initialised 1-1 mapping  // change sort_order first: sort_order.sort(function (a,b) {     // , b being indices     return data_r[a] - data_r[b]; }); 

// making new, sorted array var data_x_sorted = new array(l); (var i=0; i<l; i++)     data_x_sorted[ sort_order[i] ] = data_x[i]; // put sorted position 

if want sort data_x array itself, use "apply" algorithm showed data_r.

the question is, how can undo sort on data_r array?

either don't sort @ all, , make copy of gets sorted (or nothing @ all).

or use sort_order reverse it. need swap i , newindex (sortorder[i]) everywhere. example building new, "unsorted" (old-order) array:

var unsorted = new array(l); (var i=0; i<l; i++)     unsorted[i] = data_r[ sort_order[i] ]; // take new position