如何在typescript中扩展类型？

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

interface Employee extends Person {
  salary: number;
}

const employee: Employee = {
  name: "John",
  age: 30,
  salary: 5000,
};

class Animal {
  name: string;

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

  eat() {
    console.log("Eating...");
  }
}

class Dog extends Animal {
  breed: string;

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

  bark() {
    console.log("Barking...");
  }
}

const dog: Dog = new Dog("Max", "Labrador");
dog.eat(); // Output: Eating...
dog.bark(); // Output: Barking...

type Person = {
  name: string;
  age: number;
};

type Employee = Person & {
  salary: number;
};

const employee: Employee = {
  name: "John",
  age: 30,
  salary: 5000,
};