Add or change a value of JSON key with jQuery or JavaScript

Question

I have a JSON string(?) that I have returned from $.ajax() and named it data. Some of the values are empty and I need to add values to some of the keys and send it back to my PHP script.

I access the existing values by data.keyName. How do I add or change the values of certain keys in data?

This is what data looks like.

{
    "ID":"48",
    "userID":"0",
    "address":"750 North High Street",
    "city":"Columbus",
    "state":"OH",
    "zip":"43215",
    "lat":"39.977673",
    "lng":"-83.003357",
    "busNumber":"55",
    "isClaimed":"N",
    "whereFound":"",
    "busNum":"",
    "email":"",
    "fname":"",
    "lname":"",
    "comments":""
}

If you access the values with data.keyName, you no longer have a JSON string. You have a JavaScript object. JSON has already been parsed into an object for you. — Ateş Göral
– Ateş Göral, Commented Dec 13, 2010 at 15:23
Thanks for explaining that, Ates. I was confused about that. — JCam
– JCam, Commented Dec 13, 2010 at 15:49

cdhowie · Accepted Answer · 2010-12-13 15:10:21Z

50

Once you have decoded the JSON, the result is a JavaScript object. Just manipulate it as you would any other object. For example:

data.busNum = 12345;
...

answered Dec 13, 2010 at 15:10

cdhowie

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1 Comment

JCam Over a year ago

Why didn't I try that... Thanks!

sje397 · Accepted Answer · 2010-12-13 15:10:55Z

22

var temp = data.oldKey; // or data['oldKey']
data.newKey = temp;
delete data.oldKey;

answered Dec 13, 2010 at 15:10

sje397

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Comments

dongjie · Accepted Answer · 2016-12-28 16:00:37Z

8

It seems if your key is saved in a variable. data.key = value won't work.

You should use data[key] = value

Example:

data = {key1:'v1', key2:'v2'};

var mykey = 'key1'; 
data.mykey = 'newv1';
data[mykey] = 'newV2';

console.log(data);

Result:

{
  "key1": "newV2",
  "key2": "v2",
  "mykey": "newv1"
}

edited Dec 28, 2016 at 16:00

answered May 20, 2016 at 10:13

dongjie

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Comments

epascarello · Accepted Answer · 2010-12-13 15:11:20Z

4

Just like you would for any other variable, you just set it

alert(data.ID);
data.ID = "bar";  //dot notation 
alert(data.ID);    
data.userID = 123456;
data["address"] = "123 some street"; //bracket notation

answered Dec 13, 2010 at 15:11

epascarello

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Comments

scheffield · Accepted Answer · 2010-12-13 15:10:37Z

0

data.userID = "10";

answered Dec 13, 2010 at 15:10

scheffield

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1 Comment

elvenbyte Over a year ago

If userID exists as a key, this answer duplicates it.

Gajender Singh · Accepted Answer · 2017-01-04 11:27:08Z

0

var y_axis_name=[];

 for(var point in jsonData[0].data)
              { 
                y_axis_name.push(point);

              }

y_axis_name is having all the key name

try on jsfiddle

answered Jan 4, 2017 at 11:27

Gajender Singh

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Comments

Ridham Tarpara · Accepted Answer · 2021-07-27 12:25:19Z

0

You just set the data value like a normal javascript variable Ex:

data["userID"] = 4; // or data.userID = 4

edited Jul 27, 2021 at 12:25

Ridham Tarpara

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answered Jul 25, 2021 at 21:23

Ren Lowsphere

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Comments

Serdar Karaca · Accepted Answer · 2023-09-16 22:37:06Z

0

//We loop inside the array with "for"
for(let i = 0; i < _arrayJsonItems.length; i++)
{
    //First, we write the keys we want to delete
    delete _arrayJsonItems[i].KeyOne;
    delete _arrayJsonItems[i].KeyTwo;

    //Finally, we add new values with the same key names.
    _arrayJsonItems[i].KeyOne = "NewValue";
    _arrayJsonItems[i].KeyTwo = "NewValue";
    
}

answered Sep 16, 2023 at 22:37

Serdar Karaca

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1 Comment

Bobdabear Over a year ago

could use forEach: _arrayJsonItems.forEach((item) => { })

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