How to convert a json formatted string into a json array in javascript

Question

I am using the $.post() method to retrieve a json formatted string which looks like this:

{elementid:10},{elementid:11},{elementid:12},{elementid:14},{elementid:15}

In the success callback function of $.post(), I would like to loop the values of this json formatted string but I can't figure out how to do it.

  // data returns {elementid:10},{elementid:11},{elementid:12},{elementid:14}, etc.

  $.post('form.php',

        {'postvalues' : input_ids},

        function(data){

              var elements = Array();

              elements = [data];

              for(var i=0; i<elements.length; i++) {
                    var value = elements[i]['elementid'];
                    alert('value = '+value);
              }
  });

When I do this, instead of getting value = 10, value = 11, value = 12, etc. in the alert box, I get value = undefined

What must I change in the format of the variable 'data' so that it will be interpreted as array values and not a string?

thanks for your help

Thanks a lot guys. Problem solved using jQuery.parseJSON, adding[] and wrapping JSON keys in double quotes — Vincent
– Vincent, Commented Sep 30, 2011 at 14:42
In that case, please accept an answer as the solution to your question by clicking the green checkmark next to it @Vincent. — Alex Turpin
– Alex Turpin, Commented Sep 30, 2011 at 14:54
done, I was searching for the 'solved' button actually, thanks — Vincent
– Vincent, Commented Sep 30, 2011 at 15:15

user113716 · Accepted Answer · 2011-09-30 14:32:43Z

7

Your string isn't valid JSON if you don't have the '[' and ']' characters.

You can add those in , then parse it using the jQuery.parseJSON()^[docs] method.

elements = jQuery.parseJSON( '[' + data + ']' );

...but it would be better if you sent correct JSON data from the server.

Also, your JSON keys must be wrapped in double quotes.

{"elementid":10},{"elementid":11},{"elementid":12},{"elementid":14},{"elementid":15}

answered Sep 30, 2011 at 14:32

user113716

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Comments

Vivin Paliath · Accepted Answer · 2011-09-30 14:33:23Z

1

Your query isn't returning valid JSON. It should be [{"elementid":10},{"elementid":11},{"elementid":12},{"elementid":14},{"elementid":15}] and not {elementid:10},{elementid:11},{elementid:12},{elementid:14},{elementid:15}. Is there any way you can fix that? Otherwise, you will have to do this:

elements = jQuery.parseJSON("[" + data + "]");

The right thing to do, however, is to return valid JSON from the server (if you have any control over that).

answered Sep 30, 2011 at 14:33

Vivin Paliath

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Rene Pot · Accepted Answer · 2011-09-30 14:31:42Z

0

use JSON.parse(data) to put a string which contains a JSON object in a variable

answered Sep 30, 2011 at 14:31

Rene Pot

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Richard Dalton · Accepted Answer · 2011-09-30 14:32:31Z

0

Try this, it looks like you are getting passed an array (apart from the missing surrounding []), and if you tell jquery that it's json it'll parse it for you properly:

$.post('form.php', {'postvalues' : input_ids}, function(data){              
    for(var i=0; i<data.length; i++) {
        var value = data[i]['elementid'];
        alert('value = '+value);
    }
}, 'json'); // telling it that the content received is json

answered Sep 30, 2011 at 14:32

Richard Dalton

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Comments

Bene · Accepted Answer · 2011-09-30 14:41:13Z

0

Use the "for in" statement. Such as:

for (var x in data) {
    console.log(data[x]['elementid']);
}

I tested it and it perfectly worked! Hope this helps.

Ps. Console.log() output the result in the browser console (so it won't work in IE, of course).

answered Sep 30, 2011 at 14:41

Bene

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