Like this

Copyjsondata.FDamount = 'false';
// or
jsondata['FDamount'] = 'false';

Could you do the following:

obj = {
    "1":"aa",
    "2":"bb"
};


var newNum = "3";
var newVal = "cc";


obj[newNum] = newVal;



alert(obj["3"]); // this would alert 'cc'

I would use Object.assign.

see code

const data = [{ a: 1, b: 2 }, { b: 4, c: 5 }];
const data2 = {ASD:10};

for (let i = 0; i < data.length; i++) {
  data[i] = Object.assign(data[i], data2);
}

console.log(data);

See link.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

There are two ways for adding new key value pair to Json Object in JS

var jsObj = {
    "workbookInformation": {
        "version": "9.1",
        "source-platform": "win"
    },
    "datasources1": {

    },
    "datasources2": {

    }
}

1.Add New Property using dot(.)

jsObj.workbookInformation.NewPropertyName ="Value of New Property"; 

2.Add New Property specifying index like in an arrays .

jsObj["workbookInformation"]["NewPropertyName"] ="Value of New Property"; 

Finally

 json = JSON.stringify(jsObj);
 console.log(json)

You could use Array.push() for this, for example:

if (obj[li.parentId]) {
    obj[li.parentId] = obj[li.parentId].push(li);
}
else {
    obj[li.parentId] = [li]; //note adding an array of obj, not obj
}

Another way is Array.concat() - which in this case will look the same

reference is here

The = [i] is what's causing the problem, at least in part. However, this isn't very JavaScript-y; you simply use Array.prototype.map instead:

object = object.map((value,index) => ({ ...value, ABC: index }));

Here we use Array.prototype.map, which uses a callback function to determine what the new value should be based on the old value. (params) => ({...})) is an arrow function. {...value} copies the old values to a new object (shallow copy) so we can work on the data, and then we assign the new property as well (, ABC: index).

This is the easiest way and it's working to me.

var testJson = {
        "name": "John Smith",
        "age": 32,
        "employed": true,
        "address": {
            "street": "701 First Ave.",
            "city": "Sunnyvale, CA 95125",
            "country": "United States"
        },
        "children": [
            {
                "name": "Richard",
                "age": 7
            },
            {
                "name": "Susan",
                "age": 4
            },
            {
                "name": "James",
                "age": 3
            }
        ]
    };
    testJson.collegeId = {"eventno": "6062","eventdesc": "abc"};

You can do something like this:

var students = [ { city: 'California', company: 'ABC'}, { city: 'LA', company: 'PQR'}, { city: 'Mumbai', company: 'XYZ'}];
        
students.forEach((obj) => {
  obj['email']= '[email protected]';
  console.log(obj);
});

// Final Output
console.log(students);

$ jq '.array[] += { new_key: 0 }' <<<"$json"
{
  "name": "foo",
  "array": [
    {
      "name": "bar",
      "thing": true,
      "new_key": 0
    },
    {
      "name": "baz",
      "thing": false,
      "new_key": 0
    }
  ]
}

That is, use += in place of +. You want to modify the array, not extract it and add to it.

Or, if you want to hard-code the key in the jq expression, pass the value on the command line:

jq --argjson newval "$somevalue" '.array[] += { new_key: $newval }' <<<"$json"

Or neater, using $ARGS.named, allowing you to change the key outside of the jq expression:

jq --argjson new_key "$somevalue" '.array[] += $ARGS.named' <<<"$json"

Change --argjson to just --arg if the value you are adding is a string.

(Note that this has nothing to do with JSON. You're not using JSON there, you're using an object initializer. JSON is a textual (not code) format, which is a subset of JavaScript's object initializer syntax.)

Do it outside the object initializer, using [] notation:

var id = $('#myInput').val();

var post = {};
post[product[id]] = 'myValue';

That will take the value (at runtime) of product[id] and use that as the key for the property. If you wanted the key to literally be product[123] when id is 123, you'd use this instead:

post['product[' + id + ']'] = 'myValue';

A more generic discussion:

var a = "foo";
var obj = {};
obj[a] = "bar";
console.log(obj.foo); // "bar"

JavaScript allows you to specify property keys in two ways: Using dotted notation and a literal (obj.foo), or using bracketed notation and a string (obj["foo"]). In the latter case, the string doesn't have to be a string literal, it can be the result of any expression.

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;
...