Ts有趣现象

今日学习Ts的接口，我发现了一个有趣的Ts怪像，直接上代码

interface animalConstructor {
    new (name:string,sing:string):animalInterface
}

interface animalInterface {
    bark():void;
}
class Dog implements animalInterface{
    name:string
    sing:string
    constructor(n:string,sing:string) {
        this.name = n
        this.sing = sing
    }
    bark() {
        console.log(`${this.name}${this.sing}`)
    }
}
class Cat {
    name:string
    sing:string
    constructor(name:string,sing:string) {
        this.name = name
        this.sing = sing
    }
    bark(): void {
        console.log(`${this.name}${this.sing}`)
    }
}
/**
 * 我发现个有趣的事情，即便类没有申明implement animalConstructor，但是自身的Constructor和animalConstructor一样，
 * 也没有申明implement animalInterface ，只是存在同样的方法，也可以正常执行；Cat类什么也没申明实现，却可以正常运行
 * */
function animalBark(animal:animalConstructor,n:string,s:string):animalInterface {
    return new animal(n,s)
}
let dog = animalBark(Dog,'狗','汪汪')
let cat = animalBark(Cat,'猫','喵喵')
dog.bark()
cat.bark()