类字段默认值

class Person {
  name = 'John Doe';
  age = 30;
  hobbies = ['reading', 'traveling'];

  constructor(name, age) {
    this.name = name || this.name;
    this.age = age || this.age;
  }
}

const person1 = new Person();
console.log(person1); // { name: 'John Doe', age: 30, hobbies: ['reading', 'traveling'] }

const person2 = new Person('Alice', 25);
console.log(person2); // { name: 'Alice', age: 25, hobbies: ['reading', 'traveling'] }

class Person {
  #defaultHobbies = ['reading', 'traveling'];

  hobbies = this.#defaultHobbies;

  constructor(hobbies) {
    if (hobbies) {
      this.hobbies = hobbies;
    }
  }
}

const person1 = new Person();
console.log(person1); // { hobbies: ['reading', 'traveling'] }

const person2 = new Person(['swimming']);
console.log(person2); // { hobbies: ['swimming'] }