Convert JavaScript variable string to JSON using JavaScript

You can use JSON.parse() please find below snippet for more information

var json = JSON.parse('{"questionId":null,"articleId":null,"questionText":"eewrr","pollType":null,"selectedOptionIds":[],"pollOptionList":[{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwe","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"rwer","selectedByUser":"N","createdDate":null,"modifiedDate":null}],"pollId":37}') 
console.log(json);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

for that purpose use

   JSON.parse()

var your_str = '{"questionId":null,"articleId":null,"questionText":"eewrr","pollType":null,"selectedOptionIds":[],"pollOptionList":[{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwe","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"rwer","selectedByUser":"N","createdDate":null,"modifiedDate":null}],"pollId":37}';
var obj = JSON.parse(your_str);
alert(obj);
//or
console.log(obj);

Here your_str is your json string.

You're going to want to parse it as an JSON Object So it's going to be:

JSON.parse('{"1": 1, "2": 2, "3": {"4": 4, "5": {"6": 6}}}', (key, value));

In your case it will be:

JSON.parse('{"questionId":null,"articleId":null,"questionText":"eewrr","pollType":null,"selectedOptionIds":[],"pollOptionList":[{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwer","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"werwe","selectedByUser":"N","createdDate":null,"modifiedDate":null},{"optionId":0,"questionId":0,"optionText":"rwer","selectedByUser":"N","createdDate":null,"modifiedDate":null}],"pollId":37}', key, value));

I hope I have provided you with enough information

use JSON.parse() for converting string to json and JSON.stringify() for converting json to string