使用带有泛型接口的 is 运算符

interface Animal {
  name: string;
}

interface Dog extends Animal {
  breed: string;
}

interface Cat extends Animal {
  color: string;
}

function isAnimal(obj: any): obj is Animal {
  return obj && typeof obj === 'object' && 'name' in obj;
}

function isDog(obj: any): obj is Dog {
  return obj && typeof obj === 'object' && 'breed' in obj;
}

function isCat(obj: any): obj is Cat {
  return obj && typeof obj === 'object' && 'color' in obj;
}

const animal: Animal = { name: 'Animal' };
const dog: Dog = { name: 'Dog', breed: 'Golden Retriever' };
const cat: Cat = { name: 'Cat', color: 'Black' };

console.log(isAnimal(animal)); // true
console.log(isDog(animal)); // false
console.log(isCat(animal)); // false
console.log(isAnimal(dog)); // true
console.log(isDog(dog)); // true
console.log(isCat(dog)); // false
console.log(isAnimal(cat)); // true
console.log(isDog(cat)); // false
console.log(isCat(cat)); // true