Answers for "parse json in callback javascript"

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

var json = $.parseJSON(request.responseText);

el.style.display = '';