es5实现继承的方法

本文讨论了 ES5 中的继承方法，重点关注三种主要方法：基于原型的继承、构造函数继承和寄生继承。文章解释了每种方法的优点和缺点，提供了代码例如

ES5继承方法

在ES5中，继承可以通过几种方法来实现：

基于原型的继承

这是最常见的方法在 ES5 中。它涉及创建一个基类（父类），然后通过创建继承基类的属性和方法的新对象来“子类化”它。这是通过操作子类对象的 __proto__ 属性来完成的。__proto__ property of the subclass objects.

<code class="javascript">const Animal = {
  eat() {
    console.log("Eating...");
  }
};

const Dog = {
  __proto__: Animal,
  bark() {
    console.log("Woof!");
  }
};

const myDog = Object.create(Dog);
myDog.eat(); // logs "Eating..."
myDog.bark(); // logs "Woof!"</code>

Constructor Inheritance

This approach involves creating a base class constructor function and then extending it by defining a new constructor function that takes the base class constructor as an argument and adds additional properties and methods.

<code class="javascript">function Animal() {
  this.eat = function() {
    console.log("Eating...");
  }
}

function Dog(name) {
  Animal.call(this);
  this.name = name;
  this.bark = function() {
    console.log("Woof!");
  }
}

const myDog = new Dog("Luna");
myDog.eat(); // logs "Eating..."
myDog.bark(); // logs "Woof!"</code>

Parasitic Inheritance

This approach involves creating a temporary object that inherits from the base class and then uses that object to create the desired subclass. It is similar to prototype-based inheritance, but instead of modifying the __proto__

<code class="javascript">const Animal = {
  eat() {
    console.log("Eating...");
  }
};

const Dog = (function() {
  function AnimalProxy() {}
  AnimalProxy.prototype = Animal;
  const proxy = new AnimalProxy();
  proxy.bark = function() {
    console.log("Woof!");
  }
  return proxy;
})();

const myDog = Object.create(Dog);
myDog.eat(); // logs "Eating..."
myDog.bark(); // logs "Woof!"</code>

构造函数继承🎜🎜此方法涉及创建一个基类构造函数，然后通过定义一个采用基类的新构造函数来扩展它类构造函数作为参数并添加附加属性和方法。🎜rrreee🎜寄生继承🎜🎜此方法涉及创建一个从基类继承的临时对象，然后使用该对象创建所需的子类。它类似于基于原型的继承，但它不是修改 __proto__ 属性，而是创建一个新对象，充当基类和子类之间的桥梁。🎜rrreee

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