Defining getters and setters in ES6 class

class Person {
  constructor(firstname, lastname) {
    this._firstname = firstname;
    this._lastname = lastname;
  }

  get firstname() {
    return this._firstname;
  }

  set firstname(name) {
    this._firstname = name;
  }

  get lastname() {
    return this._lastname;
  }

  set lastname(name) {
    this._lastname = name;
  }
}

let person = new Person('John', 'Doe');

console.log(person.firstname, person.lastname); // John Doe

person.firstname = 'Foo';
person.lastname = 'Bar';

console.log(person.firstname, person.lastname); // Foo Bar