javascript up. public methods

user.js

var User = (function() { // IIFE mit Closure
  var _firstname;
  var _lastname;
  
  function User(firstname, lastname) {
    _firstname = firstname;
    _lastname = lastname;
  }
  
  User.prototype.getFullName = function() {
    return _lastname + ', ' + _firstname;
  }
  
  return User;
})();

// Beispiel
var user = new User('Max', 'Mustermann');

user._firstname = 'Peter'; // Hat keine Auswirkungen...

console.log(user.getFullName()); // Mustermann, Max