How to sort an (associative) array by value?

Question

Possible Duplicate:
How to sort an associative array by its values in Javascript?

So first off I know technically Javascript doesn't have associative arrays, but I wasn't sure how to title it and get the right idea across.

So here is the code I have,

var status = new Array();
status['BOB'] = 10
status['TOM'] = 3
status['ROB'] = 22
status['JON'] = 7

And I want to sort it by value such that when I loop through it later on ROB comes first, then BOB, etc.

I've tried,

status.sort()
status.sort(function(a, b){return a[1] - b[1];});

But none of them seem to actually DO anything.

Printing the array out to the console before and after result in it coming out in the same order.

That is the wrong usage of JS arrays. Only use numeric keys with arrays. `.sort` does not do anything because strictly speaking your array does not have any elements. You have to use objects in this case. I recommend to read [MDN - Working with Objects](https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Working_with_Objects). — Felix Kling, Oct 08 '12 at 19:18
Also: [Sorting JavaScript Object by property value](http://stackoverflow.com/questions/1069666/sorting-javascript-object-by-property-value). — Felix Kling, Oct 08 '12 at 19:22
Although marked as a duplicate the solution(s) presented below are not mentioned in the duplicate. — PopeJohnPaulII, Oct 08 '12 at 23:23
[This](http://stackoverflow.com/a/1069840/218196) is pretty much the same as suggested in all the answers below. It just uses an array of arrays instead of an array of objects. It's a subtle difference which does not change the big picture of the solution. Same goes for [the accepted answer in the duplicate question](http://stackoverflow.com/a/5200010/218196), it just provides a way of programmatically converting an object into an array of arrays... which is more useful than a hardcoded example only. All the information here is provided in the other questions as well. — Felix Kling, Oct 08 '12 at 23:51
Please have a look to my answer https://stackoverflow.com/a/51116578/1078556 — danicotra, Jun 30 '18 at 16:27

saml · Accepted Answer · 2012-10-08T19:29:51.000

25

Arrays can only have numeric indexes. You'd need to rewrite this as either an Object, or an Array of Objects.

var status = new Object();
status['BOB'] = 10
status['TOM'] = 3
status['ROB'] = 22
status['JON'] = 7

or

var status = new Array();
status.push({name: 'BOB', val: 10});
status.push({name: 'TOM', val: 3});
status.push({name: 'ROB', val: 22});
status.push({name: 'JON', val: 7});

If you like the status.push method, you can sort it with:

status.sort(function(a,b) {
    return a.val - b.val;
});

edited Oct 08 '12 at 19:29

answered Oct 08 '12 at 19:23

saml

6,702
1
34
30

I like this (Array) approach, what would be the proper way to call and sort by `val`? – PopeJohnPaulII Oct 08 '12 at 19:28
I've updated my answer to include sorting by `val` with an Array of Objects. – saml Oct 08 '12 at 19:30
Great & Simple solution. – Ahsan May 14 '13 at 10:56
and the same sort for the "Object method"? – Piero Alberto Jul 03 '14 at 07:57
@PieroAlberto No, key order cannot be depended on in Objects. Objects are more or less an unordered set of Key-Value pairs. [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in) covers this well. – saml Jul 07 '14 at 18:37

score 3 · Answer 2 · answered Oct 08 '12 at 19:29

"Arrays" in javascript are numerically indexed. "Objects" are what you would would call associative array. "Objects" are inherently unordered.

So to do this you would need to change your data structure a bit.

var arr = []; // Array

// push a few objects to the array.
arr.push({name: 'BOB', age: 10});
arr.push({name: 'TOM', age: 3});
arr.push({name: 'ROB', age: 22});
arr.push({name: 'JON', age: 7});

var sorted = arr.sort(function(a, b) {
  return a.age - b.age;
});

console.log(sorted);

enter image description here

How to sort it by name? – Muneem Habib Jul 28 '16 at 10:41 — Muneem Habib, Jul 28 '16 at 10:41

score 2 · Answer 3 · answered Oct 08 '12 at 19:26

First - It's incorrect to create a Array to use it as a Mapping. Instead use Object:

var status = {};
status['BOB'] = 10;

The Array is a class with logic to handle numeric-sequential indexes.

Now answering your response, Mappings have no order, there is no guarantee about the order it will iterate so there is no such thing as "sorting a mapping"

I sugest you to use a array with objects with key, value:

var status = [];
status.push({ key: 'BOB', value: 10 });

Or two arrays:

var status = {
    keys: [],
    values: []
};
status.keys.push('BOB');
status.value.push(10);

It's up to your needs.

score 1 · Answer 4 · answered Oct 08 '12 at 19:27

You should use JavaScript Object inside Array: jsfidle

       var status = new Array();
    status.push({key: 'BOB', value: 10});
    status.push({key: 'TOM', value: 3});
    status.push({key: 'ROB', value: 22});
    status.push({key: 'JON', value: 7});
   status.sort(function(a, b){

       if(a.value > b.value){
        return -1;
       }
        else if(a.value < b.value){
        return 1;
       } 
       return 0;
    });

This is good for String comparison – cw24 Feb 05 '16 at 13:54 — cw24, Feb 05 '16 at 13:54

How to sort an (associative) array by value?

4 Answers4

Linked