Testing for an empty array object in JSON with jQuery

Question

I have a request that returns a JSON object with a single property which is an array. How can I test if the array is empty?

With jQuery code like:

 $.getJSON(
            jsonUrl,
            function(data) {
                if (data.RoleOwners == [ ]) {
                    $('<tr><td>' + noRoleOwnersText + '</td></tr>').appendTo("#roleOwnersTable tbody");
                    return;
                }
                $.each(data.RoleOwners, function(i, roleOwner) {
                    var tblRow =
                    "<tr>"
                    + "<td>" + roleOwner.FirstName + "</td>"
                    + "<td>" + roleOwner.LastName + "</td>"
                    + "</tr>"
                    $(tblRow).appendTo("#roleOwnersTable tbody");
                });

what can I put instead of if(data.RoleOwners == [ ]) to test if the RoleOwners is an empty array?

Thanks, Matt

Svante Svenson · Accepted Answer · 2010-07-12T16:05:39.500

26

(data.RoleOwners.length === 0)

edited Jul 12 '10 at 16:05

answered Dec 02 '08 at 17:59

Svante Svenson

12,315
4
41
45

1

I don't understand. Why -1? „![].length“ — would be shorter and correctly, imho. – Ed Gomoliako Sep 02 '09 at 11:43
Agreed, should be .length === 0, or ![].length as said above. Either way this question is not about JSON objects at all, but Javascript arrays. – balupton Jul 11 '10 at 13:37
1

Lol thanks for that, thought I'd tried that, but I must have tried .Length instead. – mattcole Jan 19 '11 at 23:20
Cyle http://stackoverflow.com/questions/5447024/javascript-comparison-operators-identity-vs-equality – Pedro Montoto García May 30 '13 at 15:25

score 23 · Answer 2 · answered Aug 02 '11 at 11:31

23

You can also do jQuery.isEmptyObject(data.RoleOwners)

check out http://api.jquery.com/jQuery.isEmptyObject/

answered Aug 02 '11 at 11:31

Sadiksha Gautam

5,032
6
40
71

2

This answer worked when an empty array or a null array is passed through the data result (The accepted answer didn't) thanks for this – JakeJ Apr 24 '12 at 13:42

score 4 · Answer 3 · answered Sep 18 '13 at 12:17

4

below code works perfectly fine no need to write one of yours own.

   // anyObjectIncludingJSON i tried for JSON object.

         if(jQuery.isEmptyObject(anyObjectIncludingJSON))
            {
                return;
            }

answered Sep 18 '13 at 12:17

Arun Pratap Singh

3,428
30
23

Arun, I observed that you have good understanding on jQuery apis, you have always given reference of Jquery's inbuilt apis rather than re-inventing ..wheels..good – Archana Mundaye Nov 27 '15 at 07:31

score 1 · Answer 4 · answered Mar 23 '18 at 07:03

1

Check this

JSON.parse(data).length > 0

answered Mar 23 '18 at 07:03

Sameera Prasad Jayasinghe

1,690
1
13
15

score 0 · Answer 5 · answered May 15 '12 at 03:54

An array (being an object too) can have non numeric properties which are not picked up by testing for zero length. You need to iterate through the properties just like testing for an empty object. If there are no properites then the array is empty.

function isEmptyObject(obj) {
   // This works for arrays too.
   for(var name in obj) {
       return false
   }
   return true
}

Testing for an empty array object in JSON with jQuery

5 Answers5

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