Sorting Associative Array in Javascript

Question

I am new to this board have been fishing for info here for a long time and this is my first time posting here. I am in sort of a jam right now I have an array in javascript that looks like this. Each ID is accociated with a persons name

        Array
         (
            [230] => Smith, Marc-Andre 
            [11369] => Smith, Wayne 
            [12561] => Smith, Diane 
            [12637] => Smirnova, Natalie
         )

Right now the array is sorted by the index which is the ID of the person. I am wondering if its possible to sort it alphabetically such that the array now looks like

          Array
          (
             [12637] => Smirnova, Natalia 
             [12561] => Smith, Diane 
             [230] => Smith, Marc-Andre 
             [11369] => Smith, Wayne       
          )

So far I tried using array.sort() it does sort alphabetically but the ID is lost it gives me

      Array
          (
             [0] => Smirnova, Natalia 
             [1] => Smith, Diane 
             [2] => Smith, Marc-Andre 
             [3] => Smith, Wayne       
          )

This is my first time programming javascript so thanks for all the help in advance.

As a note, you should be aware that you are creating an array that is (max index + 1) in length when you do this. So, for this example, it's 12638 elements long. — Marc, Jul 08 '11 at 23:35
Actually, that's incorrect. (Most) Javascript (implementations) use sparse arrays. Array = hashtable, basically. — wmorrell, Jul 08 '11 at 23:39
@wmorrell @Marc Either of you have documentation on this? I had never considered this and am interested. Thanks. — Wiseguy, Jul 08 '11 at 23:41
http://stackoverflow.com/questions/1510778/are-javascript-arrays-sparse — wmorrell, Jul 08 '11 at 23:43
@wmorrell: you're absolutely right, someone just forgot to tell `.length` that bit of information, always throws me off that it's biggest index + 1 internally. — Marc, Jul 08 '11 at 23:47

score 2 · Answer 1 · answered Jul 08 '11 at 23:33

Store the entries as objects in an array, with ID and name properties. The JSON would look like:

[ {'id':230,'name':'Smith, Marc-Andre'}, {'id':11369,'name':'Smith, Wayne'}, {'id':12561,'name':'Smith, Diane'}, {'id':12637,'name':'Smirnova, Natalie'} ]

Then pass a function into Array.sort() to choose which property to sort on. See https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/array/sort

score 1 · Answer 2 · answered Jul 08 '11 at 23:38

You can do something like:

function arrayify(arg) {
    var ret = [];
    for (var i in arg) {
        if (!arg.hasOwnProperty(i) continue;
        ret.push({key: i, value: arg[i]});
    }
    return ret;
}

arr = arrayify(arr).sort(function(a, b) {
    return a.key.toString() - b.key.toString();
});

score 1 · Accepted Answer · answered Jul 09 '11 at 01:18

You can't use a simple array to do what you're asking for. An array is, by definition, a list of data that is ordered by the array indexes. You are asking for it to be ordered by something other than the array indexes. I think the simplest way to store it would end up like this:

   var myData = [
        [12637, "Smirnova, Natalia"], 
        [12561, "Smith, Diane"], 
        [230, "Smith, Marc-Andre"], 
        [11369, "Smith, Wayne"]
    ];

So, it would be an array of arrays, where each sub-array contains two items, the first is the id, the second is the name. This is a similar, but slightly different form what wmorrell proposed.

You can then sort the data by the last name by passing a custom comparision into the sort routine like this:

// custom sort (assumes all data is fully formed)
// sorts in ascending order by the 2nd item in each embedded array
    myData.sort(function(a,b) {
      if (a[1] < b[1]) return(-1);
      if (a[1] > b[1]) return(1);
      return(0); 
    });

Sorting Associative Array in Javascript

3 Answers3