Getter / Setter

• get：將定義在物件的 method 用 property 取值的方式做呼叫。

• set：將定義在物件的 method 用 property 存值的方式做呼叫。

使用 get 或 set 的好處是，可以在每次存取 property 的時候，執行一些邏輯或 side effect。

class Person {
  constructor(firstName, lastName) {
    this._firstName = firstName;
    this._lastName = lastName;
  }

  // Getter for first name
  get firstName() {
    return this._firstName;
  }

  // Setter for first name
  set firstName(newFirstName) {
    this._firstName = newFirstName;
  }

  // Getter for last name
  get lastName() {
    return this._lastName;
  }

  // Setter for last name
  set lastName(newLastName) {
    this._lastName = newLastName;
  }

  // Getter for full name
  get fullName() {
    return `${this._firstName} ${this._lastName}`;
  }
}

const person1 = new Person('John', 'Doe');
console.log(person1.fullName);  // Output: "John Doe"

person1.firstName = 'Jane';
console.log(person1.fullName);  // Output: "Jane Doe"