title: "undefined" in get of Object.defineProperty in Constructor
body: <p>I can not understand what I make wrong in way to display current values of firstName and lastName methods. For now I have an error in jone.Name and jone.last, because they get - undefined.</p>
  
  <pre><code>function User(fullName) {
    this.fullName = fullName.split(' ');
  
    Object.defineProperty(this, 'firstName', {
      get: function() {
          this.firstName = this.fullName[0];
          return this.firstName;
      }
    });
  
    Object.defineProperty(this, 'lastName', {
      get: function() {
          this.lastName = this.fullName[1];
          return this.lastName;
      }   
    });
  
  }
  
  var jone= new User("Jone Coven");
  
  console.log(jone.fullName);
  console.log(jone.firstName);
  console.log(jone.lastName);
  </code></pre>