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How to pass variable to JSON without printing it as String

How to pass variable to JSON object and print it like JSON object?
I simply want to pass variable value in JSON and print it like JSON which can also be used in console.table(obj)
With Stringify:
var name = "someName";
const json = JSON.stringify('{"result":'+name+', "count":42}');
const obj = JSON.parse(json);
console.log(obj);
Without stringify
var name = "someName";
const json = '{"result":'+name+', "count":42}';
const obj = JSON.parse(json);
console.log(obj);
Using \"variableName\" it gets value in \"...\" and not the variable value
var name = "someName";
const json = '{"result":\"name\", "count":42}';
const obj = JSON.parse(json);
console.log(obj);
Solution:
var debugJSON = [];
var section_number = 1;
var i = 25;
var x = section_number-i;
tempJSON = {
"section" : section_number,
"index" : i,
"fieldname" : x,
"isValid" : "not required"
};
debugJSON.push(tempJSON);
console.log(debugJSON);
//console.table(debugJSON); //Problematic on Chrome Browser and Stack Overflow

JSON is a text representation of some data structure.
Unless you write a JSON encoder (and you don't), you don't have any reason to produce JSON manually. Attempting to generate JSON using string concatenation fails if the variable strings (name in this case) contain quotes or backslash. Escaping them could produce valid results but the code becomes bloated and difficult to read without any gain.
JavaScript provides the method JSON.stringify() to produce a JSON from any data and this is the best way to generate JSONs.
All you have to do is to build the data structure that you need to encode. In your example, the data structure is an object:
let name = "someName";
const original = {
result: name,
count: 42,
}
// encode
const json = JSON.stringify(original);
console.log(json);
// decode
data = JSON.parse(json);
console.log(data);
Running the code snippet here in page is not relevant because the output that it produces looks similar for both calls of console.log().
Run the code using Node.js or run it in the browser's console to see the values of json (it is a string) and data (it is an object).

A JSON is quite literally a JavaScript object, so you don't treat it as a string, you work with objects, which you can later stringify if need be.
In your case, you don't want to pass a variable in a string, you should pass it in an object like so:
// Declaration of name
let name = 'someName';
// Create object and store name
const json = {
result: name,
count: 42
};
// Log object as JSON and as string
console.log(json);
console.log(JSON.stringify(json));
The first log returns your object as exactly that, an object, the second log, converts it into a string to do so as you please with it!

how to get required output from json stringify array

My array look like this after use this code -:
var array=xmlhttrequest.responseText;
console.log(array);
["{\"result\":{\"isvalid\":true,\"address\":\"3EL5SKSjEzFQDBmXA5JFbsZu48vKnNSdDH\",\"scriptPubKey\":\"a9148aa3d53255b44655f82d163f37ecb68057f2edf487\",\"ismine\":false,\"iswatchonly\":false,\"isscript\":true},\"error\":null,\"id\":\"curltest\"}\n"]
I want value of isvalid , how can i get this .

That's a strange response. It's a stringified array, and that array contains a single item, which is another stringified object. Here's one option:
const responseText = String.raw`["{\"result\":{\"isvalid\":true,\"address\":\"3EL5SKSjEzFQDBmXA5JFbsZu48vKnNSdDH\",\"scriptPubKey\":\"a9148aa3d53255b44655f82d163f37ecb68057f2edf487\",\"ismine\":false,\"iswatchonly\":false,\"isscript\":true},\"error\":null,\"id\":\"curltest\"}\n"]`;
const [ stringItem ] = JSON.parse(responseText);
const itemObj = JSON.parse(stringItem);
const isvalid = itemObj.result.isvalid;
console.log(isvalid);
Note: While testing like this, you have to use String.raw so that the single backslashes are interpreted as literal backslashes and not unnecessary escape characters

The whole thing is an array as you can see it is wrapped inside [ ]. The inner content is a string, so you need to JSON.parse to convert into an object. Here is how you will get it JSON.parse(myData[0]).result.isvalid
var myData = ["{\"result\":{\"isvalid\":true,\"address\":\"3EL5SKSjEzFQDBmXA5JFbsZu48vKnNSdDH\",\"scriptPubKey\":\"a9148aa3d53255b44655f82d163f37ecb68057f2edf487\",\"ismine\":false,\"iswatchonly\":false,\"isscript\":true},\"error\":null,\"id\":\"curltest\"}\n"];
console.log("Is Valid: "+JSON.parse(myData[0]).result.isvalid);

use JSON.parse:
var obj = JSON.parse(array);
but I would try and eliminate all the unnecessary chars before using string.replace:
var json = array.replace("\", "");

Get data from this json string

I have a json string
["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"]
I need to get at the data only and I want to extract the string to get the following :
https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg
I have tried to use JSON.parse but this does not seem to work
Any help woul dbe appreciated

[] represents an array on JSON. {} represents an Object.
So in order to fetch the first element from you json string, you have to parse the string as a JSON element ;
var arr = JSON.parse('["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"]');
OR when you HAVE a json array already;
var arr = ["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"];
Then, go on and fetch the first value from your array which has index 0 as in all programming languages.
var url = arr[0];

It's seems to be a normal array not a JSON, but if you want you can treat it as JSON:
var image = JSON.parse('["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"]')[0];
console.log(image); //https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg

Be aware of the difference between an array, and a JSON object.
I have given some examples of the differences and how to access them.
// This is an array containing 1 value.
myobj = ["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"];
// it can be accessed by either the array name (since it only hase one value) or the array name and index of the value in cases where the array actually has more than one value.
var example1 = [myobj];
document.write("This is my single value array:<br>" + example1 + "<br><br>");
// This is probably best practice regardless of the number of items in the array.
var example2 = myobj[0];
document.write("Now im specificing the index, incase there are more that one urls in the array:<br>" + example1 + "<br><br>");
// This is a JSON object
myJsonObj = {"url":"https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"}
// You access the value of the URL like this:
var example3 = myJsonObj.url;
document.write("Here is the value from a JSON object:<br>" + example3 );
Hope this helps

Just use parse function:
var text = '["https://upload.wikimedia.org/wikipedia/commons/5/57/Cassini_Helene_N00086698_CL.jpg"]';
var obj = JSON.parse(text);
https://jsfiddle.net/esouc488/1/

Regex extract contents

So, I have the following data here:
{"screenName":"fubars","msgHash":"C5STUYqhjzNiP6LLVbPlTF3zYLVYXHrm","imgURL":null,"userColor":"#00a4a0","messageTime":"2:50 PM","messageDate":1442256635621,"accountType":"m","accountTypeID":"z2ZkdXqck-JO45hqXVXH","isModerator":"","badges":""
I've written some regex to extract strings, but if I search for example "screenName" it gets the "fubars" part and the rest of the string, I only want the "fubars" part...
code:
function extractSummary(iCalContent, what) {
eval("var rxm = /\""+what+"\": \"(.*)\"/g");
console.log(rxm);
setTimeout(function(){},1500);
var arr = rxm.exec(iCalContent);
return arr[1];
}

If you have some data in the form of a JSON string, you can use JSON.parse to convert it into a JSON object. You can then use dot or index property getters.
var jsonString = '{"screenName":"fubars","msgHash":"C5STUYqhjzNiP6LLVbPlTF3zYLVYXHrm"}';
var jsonObject = JSON.parse(jsonString);
console.log(jsonObject.screenName);
console.log(jsonObject['screenName']);
There's no need to use regexes here.

Parse JSON array from string

I want to convert the following string to an array
var string = '["YES","NO"]';
How do I do this?

use the global JSON.parse method
JSON.parse('["YES","NO"]'); // returns ["YES", "NO"]
You can also use the JSON.stringify method to write the array back to a string if thats how you are storing it.
JSON.stringify(["YES", "NO"]); // returns '["YES", "NO"]'

var str= '["YES","NO"]';
var replace= str.replace(/[\[\]]/g,'');
var array = replace.split(',');
Fiddle : http://jsfiddle.net/9amstq41/

You can also use $.parseJSON:
var string = '["YES","NO"]';
var array = $.parseJSON(string);