如何在TypeScript中区分不同的对象类型？

interface Dog {
  type: 'dog';
  bark: () => void;
}

interface Cat {
  type: 'cat';
  meow: () => void;
}

type Animal = Dog | Cat;

function handleAnimal(animal: Animal) {
  if (animal.type === 'dog') {
    animal.bark();
  } else if (animal.type === 'cat') {
    animal.meow();
  }
}

const myDog: Dog = { type: 'dog', bark: () => console.log('Woof!') };
const myCat: Cat = { type: 'cat', meow: () => console.log('Meow!') };

handleAnimal(myDog); // Output: Woof!
handleAnimal(myCat); // Output: Meow!

type Dog = {
  bark: () => void;
};

type Cat = {
  meow: () => void;
};

type Animal = Dog | Cat;

function isDog(animal: Animal): animal is Dog {
  return (animal as Dog).bark !== undefined;
}

function handleAnimal(animal: Animal) {
  if (isDog(animal)) {
    animal.bark();
  } else {
    (animal as Cat).meow();
  }
}

const myDog: Dog = { bark: () => console.log('Woof!') };
const myCat: Cat = { meow: () => console.log('Meow!') };

handleAnimal(myDog); // Output: Woof!
handleAnimal(myCat); // Output: Meow!

type Dog = {
  bark: () => void;
};

type Cat = {
  meow: () => void;
};

type Animal = Dog | Cat;

function handleAnimal(animal: Animal) {
  if ('bark' in animal) {
    animal.bark();
  } else {
    animal.meow();
  }
}

const myDog: Dog = { bark: () => console.log('Woof!') };
const myCat: Cat = { meow: () => console.log('Meow!') };

handleAnimal(myDog); // Output: Woof!
handleAnimal(myCat); // Output: Meow!

class Dog {
  bark() {
    console.log('Woof!');
  }
}

class Cat {
  meow() {
    console.log('Meow!');
  }
}

type Animal = Dog | Cat;

function handleAnimal(animal: Animal) {
  if (animal instanceof Dog) {
    animal.bark();
  } else if (animal instanceof Cat) {
    animal.meow();
  }
}

const myDog = new Dog();
const myCat = new Cat();

handleAnimal(myDog); // Output: Woof!
handleAnimal(myCat); // Output: Meow!