How to get json key and value in javascript?

//By using jquery json parser    
var obj = $.parseJSON('{"name": "", "skills": "", "jobtitel": "Entwickler", "res_linkedin": "GwebSearch"}');
alert(obj['jobtitel']);

//By using javasript json parser
var t = JSON.parse('{"name": "", "skills": "", "jobtitel": "Entwickler", "res_linkedin": "GwebSearch"}');
alert(t['jobtitel'])

Check this jsfiddle

As of jQuery 3.0, $.parseJSON is deprecated. To parse JSON strings use the native JSON.parse method instead.

Source: http://api.jquery.com/jquery.parsejson/

you have parse that Json string using JSON.parse()

..
}).done(function(data){
    obj = JSON.parse(data);
    alert(obj.jobtitel);
});