Inheritance

需要用到共同屬性的時候用 extends

call super() 是為了 call 上一層的 constructor
而且需要將 name 傳上去

class Dog {
  constructor(name) {
    this.name = name
  }

  sayHello() {
    console.log(this.name)
  }
}

class BlackDog extends Dog {
  constructor(name) {
    super(name)
    this.sayHello()
  }
  test() {
    console.log('test', this.name)
  }
}
const d = new BlackDog('hello') 
// hello