Accessing elements of JSON object without knowing the key names

Question

Here's my json:

{"d":{"key1":"value1",
      "key2":"value2"}}

Is there any way of accessing the keys and values (in javascript) in this array without knowing what the keys are?

The reason my json is structured like this is that the webmethod that I'm calling via jquery is returning a dictionary. If it's impossible to work with the above, what do I need to change about the way I'm returning the data?

Here's an outline of my webmethod:

<WebMethod()> _
Public Function Foo(ByVal Input As String) As Dictionary(Of String, String)
    Dim Results As New Dictionary(Of String, String)

    'code that does stuff

    Results.Add(key,value)
    Return Results
End Function

*"accessing the keys and values (in javascript) in this array"* - what array..? — T J, Oct 11 '14 at 07:09

score 75 · Accepted Answer · answered Feb 25 '11 at 05:14

75

You can use the for..in construct to iterate through arbitrary properties of your object:

for (var key in obj.d) {
    console.log("Key: " + key);
    console.log("Value: " + obj.d[key]);
}

answered Feb 25 '11 at 05:14

Ates Goral

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2

Perfect. Do I still need to use a `for in` if there is only one key value pair? – Radu Feb 25 '11 at 05:20
@Radu You can't access the properties of an object with indices, so you will need to get the key(s) using a for...in. – Xenethyl Feb 25 '11 at 05:28
What if the JSON has a list of objects and you want to get the object names? Like {"d":{"key1":"value1","key2":"value2"},"e":{"key1":"value1","key2":"value2"}} and you want name of d and e, but you don't know they're called d and e at runtime. – David May 02 '12 at 06:28
The "key" variable in the top-level iteration would give you the "object names". – Ates Goral May 02 '12 at 14:51
1

You might need to use `obj.d.hasOwnProperty(key)` inside for block to get rid of the inner private properties. – cackharot Aug 19 '14 at 05:09
2

This has saved me over 6 hours of searching. Works well with deep children in firebase tree. – Akah Mar 24 '17 at 12:21

Xenethyl · Answer 2 · 2011-02-25T05:20:18.950

13

Is this what you're looking for?

var data;
for (var key in data) {
   var value = data[key];
   alert(key + ", " + value);
}

edited Feb 25 '11 at 05:20

answered Feb 25 '11 at 05:12

Xenethyl

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Tip: Don't call JavaScript objects JSON objects. JSON is the transport format. Once parsed, there's no JSON. – Ates Goral Feb 25 '11 at 05:14
1

Tip2: A more concise way to alert multiple values: `alert([key, value])` – Ates Goral Feb 25 '11 at 05:16
1

@Ates Goral My implication with the var name was that it contained the JSON data, not that it was a JSON object. Poor choice, I suppose. – Xenethyl Feb 25 '11 at 05:19
Thanks. Accepted the other answer as it was slightly better tuned to my json data. – Radu Feb 25 '11 at 05:33
1

@Radu You're welcome, and no problem. Glad we were able to help you. – Xenethyl Feb 25 '11 at 05:34

Shivam Chhetri · Answer 3 · 2020-03-31T06:54:12.330

6

{
  "d":{
     "key1":"value1",
     "key2":"value2"
    }
}

To access first key write:

   let firstKey=Object.keys(d)[0];

To access value of first key write:

let firstValue= d[firstKey];

edited Mar 31 '20 at 06:54

answered Aug 04 '19 at 09:14

Shivam Chhetri

677
11
16

score 3 · Answer 4 · edited Oct 11 '14 at 07:12

By using word "b", You are still using key name.

var info = {
"fname": "Bhaumik",
"lname": "Mehta",
"Age": "34",
"favcolor": {"color1":"Gray", "color2":"Black", "color3":"Blue"}
};

Look at the below snippet.

for(key in info) {
  var infoJSON = info[key];
  console.log(infoJSON);
}

Result would be,

Bhaumik
Mehta
Object {color1: "Gray", color2: "Black", color3: "Blue"}

Don’t want that last line to show up? Try following code:

for(key in info) {
  var infoJSON = info[key];
    if(typeof infoJSON !== "object"){
       console.log(infoJSON);
  }
}

This will eliminate Object {color1: “Gray”, color2: “Black”, color3: “Blue”} from showing up in the console.

Now we need to iterate through the variable infoJSON to get array value. Look at the following whole peace of code.

for(key in info) {
    var infoJSON = info[key];
    if (typeof infoJSON !== "object"){
       console.log(infoJSON);
    }
 }

for(key1 in infoJSON) {
    if (infoJSON.hasOwnProperty(key1)) {
       if(infoJSON[key1] instanceof Array) {
          for(var i=0;i<infoJSON[key1].length;i++) {
             console.log(infoJSON[key1][i]);
          }
        } else {console.log(infoJSON[key1]);}
    }
 }

And now we got the result as

Bhaumik
Mehta
Gray
Black
Blue

If we use key name or id then it’s very easy to get the values from the JSON object but here we are getting our values without using key name or id.

KARTHIKEYAN.A · Answer 5 · 2018-02-20T09:33:11.617

3

Use for loop to achieve the same.

var dlist = { country: [ 'ENGLAND' ], name: [ 'CROSBY' ] }

for(var key in dlist){
     var keyjson = dlist[key];
     console.log(keyjson)
   }

edited Feb 20 '18 at 09:33

answered Dec 22 '16 at 11:00

KARTHIKEYAN.A

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Accessing elements of JSON object without knowing the key names

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