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i have a JSON object that gets returned by an AJAX request and I am having some trouble with the .length because it keeps returning undefined. Just wondering if I'm using it right:

console.log(data.length);
console.log(data.phones.length);

They both return undefined even though they are valid objects.

Update:
Sample of the JSON object returned:

{"reqStatus":true,"phones":{"one":{"number":"XXXXXXXXXX","type":"mobile"},"two":{"number":"XXXXXXXXXX","type":"mobile"}}}

i have a JSON object that gets returned by an AJAX request and I am having some trouble with the .length because it keeps returning undefined. Just wondering if I'm using it right:

console.log(data.length);
console.log(data.phones.length);

They both return undefined even though they are valid objects.

Update:
Sample of the JSON object returned:

{"reqStatus":true,"phones":{"one":{"number":"XXXXXXXXXX","type":"mobile"},"two":{"number":"XXXXXXXXXX","type":"mobile"}}}

• javascript
• json

Share Improve this question Follow edited Apr 1, 2021 at 16:17 Syscall 19.8k1010 gold badges4343 silver badges5757 bronze badges asked Jul 20, 2011 at 1:44 nkcmrnkcmr 11k2525 gold badges6868 silver badges8787 bronze badges 3

• Can you post a sample of the JSON returned? – Joe Commented Jul 20, 2011 at 1:48
• I'm not sure, wasn't me. I think your question is fine, as well. – Joe Commented Jul 20, 2011 at 18:54
• To those came here via Google: Try solutions given below but check spellings also before that. In my case I was writing .lenght instead of .length and typescript interpreter never complained. Welcome to scripting world! – Atul Commented Feb 8, 2022 at 18:29

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9 Answers 9

Sorted by: Reset to default 717

You can use something like this

var myObject = {'name':'Kasun', 'address':'columbo','age': '29'}

var count = Object.keys(myObject).length;
console.log(count);

Your problem is that your phones object doesn't have a length property (unless you define it somewhere in the JSON that you return) as objects aren't the same as arrays, even when used as associative arrays. If the phones object was an array it would have a length. You have two options (maybe more).

1. Change your JSON structure (assuming this is possible) so that 'phones' becomes

   "phones":[{"number":"XXXXXXXXXX","type":"mobile"},{"number":"XXXXXXXXXX","type":"mobile"}]
   

   (note there is no word-numbered identifier for each phone as they are returned in a 0-indexed array). In this response phones.length will be valid.

2. Iterate through the objects contained within your phones object and count them as you go, e.g.

   var key, count = 0;
   for(key in data.phones) {
     if(data.phones.hasOwnProperty(key)) {
       count++;
     }
   }
   

If you're only targeting new browsers option 2 could look like this

you dont need to change your JSON format.

replace:

console.log(data.phones.length);

with:

console.log( Object.keys( data.phones ).length ) ;

Consider using underscore.js. It will allow you to check the size i.e. like that:

var data = {one : 1, two : 2, three : 3};
_.size(data);
//=> 3
_.keys(data);
//=> ["one", "two", "three"]
_.keys(data).length;
//=> 3

var json=[{"id":"431","code":"0.85.PSFR01215","price":"2457.77","volume":"23.0","total":"565.29"},{"id":"430","code":"0.85.PSFR00608","price":"1752.45","volume":"4.0","total":"70.1"},{"id":"429","code":"0.84.SMAB00060","price":"4147.5","volume":"2.0","total":"82.95"},{"id":"428","code":"0.84.SMAB00050","price":"4077.5","volume":"3.0","total":"122.32"}] 
var obj = JSON.parse(json);
var length = Object.keys(obj).length; //you get length json result 4

try this

$.parseJSON(data).length

Use this one

Object.keys(jsonObject).length

var data = {"reqStatus":true,"phones":{"one":{"number":"XXXXXXXXXX","type":"mobile"},"two":{"number":"XXXXXXXXXX","type":"mobile"}}}

console.log(Object.keys(data).length);

console.log(Object.keys(data.phones).length);

console.log(Object.keys(data.phones.two).length);

$(document).ready(function () {
    $('#count_my_data').click(function () {
        var count = 0;
        while (true) {
             try {
                var v1 = mydata[count].TechnologyId.toString();
                count = count + 1;
            }
            catch (e)
            { break; }
        }
        alert(count);
    });
});

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