How to transfer myparStn to n in myJSON.n = v;, changing it to myJSON.myparStn = v;

Hi @Manan Joshi 

Sorry for not responding in a timely manner。

I seem to see hope. But something is not right.

The key to the problem becomes how to read field names from JSON files (such as myParStn)

My target JSON is like this (for example: aa.json)

{
"myParStn": "222",
"myChaStn": "HH"
}

I followed your advice and made the following modifications:

var abc="111";
rwJSON(myparStn,abc);

function rwJSON(n,v) {
    // read the json file's contents
    var myJSON = readFile(pathToMyJSONFile);
    if (!myJSON)
        return alert('Could not read JSON file.');
    // parse as json
    myJSON = JSON.parse(myJSON);
    // input text;
    //myJSON.n = v;   
     myJSON[n] = v;  
    var f = writeFile(pathToMyJSONFile, JSON.stringify(myJSON, undefined, '\t'));
}

 The result indicates that myParStn is undefined,

So I guess, first we need to read myParStn from aa.json.
So I added in front of it:

var abc="111";
var myJSON = readFile(pathToMyJSONFile);
if (!myJSON)
return alert('Could not read JSON file.');
// parse as json
myJSON = JSON.parse(myJSON);
rwJSONw(myJSON.myParStn,abc);

The result of aajson is as follows:

{
"myParStn": "222",
"myChaStn": "HH",
"222": "111"
}

Obviously, I still haven't obtained the myParStn field itself.
I just got the original value of myParStn