Typescript如何声明一个子类类型？

class Animal {
  name: string;

  constructor(name: string) {
    this.name = name;
  }

  eat() {
    console.log(`${this.name} is eating.`);
  }
}

class Dog extends Animal {
  breed: string;

  constructor(name: string, breed: string) {
    super(name);
    this.breed = breed;
  }

  bark() {
    console.log(`${this.name} is barking.`);
  }
}

const myDog = new Dog("Max", "Labrador");
myDog.eat(); // Output: Max is eating.
myDog.bark(); // Output: Max is barking.