how to unstringify json javascript code example

Example 1: if json then parse

function isJson(str) {
    try {
        let value = JSON.parse(str);
      	return value
    } catch (e) {
        return str;
    }
}

Example 2: json parse returns object

var str = '[{"UserName":"xxx","Rolename":"yyy"}]'; // your response in a string
    var parsed = JSON.parse(str); // an *array* that contains the user
    var user = parsed[0];         // a simple user
    console.log(user.UserName);   // you'll get xxx
    console.log(user.Rolename);   // you'll get yyy