JavaScript 中的面向对象编程 (OOP)：综合指南

// 定义一个类
class Person {
  constructor(name, age) {
    this.name = name; // 属性
    this.age = age;
  }

  greet() { // 方法
    console.log(`你好，我的名字是${this.name}，我${this.age}岁了。`);
  }
}

// 创建一个对象
const person1 = new Person('Alice', 30);
person1.greet(); // 输出：你好，我的名字是Alice，我30岁了。

class BankAccount {
  #balance; // 私有属性

  constructor(initialBalance) {
    this.#balance = initialBalance;
  }

  deposit(amount) {
    this.#balance += amount;
  }

  getBalance() {
    return this.#balance;
  }
}

const account = new BankAccount(1000);
account.deposit(500);
console.log(account.getBalance()); // 1500
// console.log(account.#balance); // 错误：无法访问私有属性 '#balance'

class Animal {
  constructor(name) {
    this.name = name;
  }

  speak() {
    console.log(`${this.name} 发出声音。`);
  }
}

class Dog extends Animal {
  speak() {
    console.log(`${this.name} 汪汪叫。`);
  }
}

const dog = new Dog('Buddy');
dog.speak(); // 输出：Buddy 汪汪叫。

class Shape {
  area() {
    return 0;
  }
}

class Rectangle extends Shape {
  constructor(width, height) {
    super();
    this.width = width;
    this.height = height;
  }
  area() {
    return this.width * this.height;
  }
}

const shape = new Shape();
const rectangle = new Rectangle(10, 5);

console.log(shape.area());       // 0
console.log(rectangle.area());   // 50

class Vehicle {
  startEngine() {
    console.log('引擎启动');
  }
}

class Car extends Vehicle {
  drive() {
    console.log('驾驶汽车...');
  }
}

const car = new Car();
car.startEngine(); // 引擎启动
car.drive();       // 驾驶汽车...

class MathUtils {
  static add(a, b) {
    return a + b;
  }
}

console.log(MathUtils.add(5, 3)); // 8

function Person(name) {
  this.name = name;
}

Person.prototype.greet = function() {
  console.log(`你好，我的名字是${this.name}`);
};

const person = new Person('Alice');
person.greet(); // 你好，我的名字是Alice