Login

// pseudocode of doom

function login(username, pw, callback) {
  $.ajax(url).success(function(response) {
    if(response.code != 404 && response.code == 200) { // redundant, such dir was aus
      callback(JSON.parse(response.data));
    }
  }
}

// aufruf

login("ced", "laier321", function(data) {
  console.log("erfolgreicher aufruf");
  console.log(data);
});