Typescript:如何使用结构子类型和继承

interface Animal {
  name: string;
  age: number;
}

interface Dog {
  name: string;
  age: number;
  breed: string;
}

let animal: Animal = { name: "Tom", age: 5 };
let dog: Dog = { name: "Max", age: 3, breed: "Labrador" };

animal = dog; // 结构子类型，可以将dog赋值给animal

class Animal {
  name: string;
  age: number;

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

  eat() {
    console.log("Animal is eating.");
  }
}

class Dog extends Animal {
  breed: string;

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

  bark() {
    console.log("Dog is barking.");
  }
}

let dog = new Dog("Max", 3, "Labrador");
dog.eat(); // 继承父类的eat方法
dog.bark(); // 子类自己的bark方法