Count properties of JavaScript object

Question

My question is short and concise.

I need count the attributes of Json object, for example

 obj={
      name:'Jhon',
      age:25
 }

This must return 2, one for 'name' and ohter for 'age'. I try use.

 obj.count();
 obj.length();

But nothing...

The all solutions that I found in internet was for count elements of array.

Thanks to all!

That's not JSON. That's JavaScript. (Specifically, it's a JavaScript object initializer.) JSON is a non-code, textual data format. And in JavaScript they're called "properties," not "attributes" (not a criticism, "attributes" is a general term -- just letting you know what the precise term is). — T.J. Crowder
– T.J. Crowder, Commented Oct 1, 2013 at 21:08

PSL · Accepted Answer · 2013-10-01 21:12:53Z

11

Try Object.keys, There is no built in length property or method on Javascript object.

var propCount = Object.keys(obj).length;

Note that there is a Shim you need to add in your source code for added support for some older browsers (ex: IE < 9) . Read the documentation link from MDN

edited Oct 1, 2013 at 21:12

answered Oct 1, 2013 at 21:06

PSL

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4 Comments

LexLythius Over a year ago

I would advise not to touch Object.prototype, you will be affecting everything else with unpredictable results.

PSL Over a year ago

@LexLythius yeah you are right, it is not advisable at all to extend built in prots

LexLythius Over a year ago

Also, note that Object.keys only works with modern browsers

PSL Over a year ago

yes but there is a shim in MDN which you can add to your source in case not available.

Norbert Pisz · Accepted Answer · 2013-10-01 21:06:47Z

3

Try like this:

Object.keys(obj).length

answered Oct 1, 2013 at 21:06

Norbert Pisz

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Comments

zyglobe · Accepted Answer · 2013-10-03 20:24:11Z

2

Just to add to the Object.keys(obj).length solution, here's a polyfill for browsers that don't support Object.keys.

Object.keys = Object.keys || function(o,k,r){
    r=[];
    for(k in o){
        r.hasOwnProperty.call(o,k) && r.push(k);
    }
    return r;
}

edited Oct 3, 2013 at 20:24

answered Oct 1, 2013 at 22:03

zyglobe

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1 Comment

PSL Over a year ago

You would need to put return r outside the for loop.

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