JSON.parse(`${obj}`) code example
Example 1: 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
Example 2: what does json.parse do
The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.