javascript - 我是否误解了继承的概念？

Question

我正在尝试找出继承的正确用法。在下面的代码中，我尝试实例化我的 ReadingMaterial 类，并创建一系列书籍和杂志，继承自 ReadingMaterial。我在这里正确使用继承吗？

// Define our class with constructor
class ReadingMaterial {
    constructor(author, type, price, title){
        this.author = author;
        this.type = type;
        this.price = price;
        this.title = title;
    }
}
// variable books containing 2 different books
var books = [
    new ReadingMaterial("Lars Tvede", "Fagliteratur", "399kr","Supertrends"),
    new ReadingMaterial("Rasmmus Tantholdt", "Faglitteratur","249kr","Med åbne øjne"),
    new ReadingMaterial("Jussi Alder", "Skønlitteratur", "349kr","Offer 2117")
];
// feature that allows you to type `showMagazines();` in the console
// so we can see our magazines
function showBooks (){
    console.log(books);
};
// variable magazine containing 2 different magazines
var magazine = [
    new ReadingMaterial("Euroman", "Magasin", "99kr","Mick Øgendahl"),
    new ReadingMaterial("Alt for damerne", "Magasin", "149kr","Boligindretning")
];
// feature that allows you to type `showMagazines();` in the console
// so we can see our magazines
function showMagazines() {
    console.log(magazine);
};

Answer 1

当您有两个实体，其中一个实体派生于另一个实体时，就会发生继承。例如，当您从 parent 之一继承眼睛颜色时，那么你们都是蓝眼睛。

请看一下这个示例 ( source ):

class Animal {
  constructor(legs) {
    this.legs = legs;
  }

  run() {
    console.log(`Runs on ${this.legs} legs`);
  }
}

class Dog extends Animal {
  bark() {
    console.log("Woof!");
  }
}

const d = new Dog(4);
d.run(); // <- uses `run` method from `Animal`
d.bark(); // <- uses its own method

在您的示例中，您可以创建一个 ReadingMaterial 类，然后创建 Magazine 和 Book 等类，它们将从 继承某些内容阅读 Material .

继承是一个非常广泛且有时很复杂的概念。很容易过度使用它并将类扩展得太深(例如， Animal -> Dog -> Husky -> AlaskanHusky)并且对实际发生的情况缺乏了解。

我建议获取有关 composition over inheritance 的更多信息.