Javascript继承&应用 [英] Javascript inheritance & Apply

问题描述

我一直在研究Javascript中的设计模式，发现 http://tcorral.github.com/Design-Patterns-in-Javascript/Template/withoutHook/index.html 是一个很好的来源。

I have been looking into design patterns in Javascript and found http://tcorral.github.com/Design-Patterns-in-Javascript/Template/withoutHook/index.html to be a great source.

Anyonne可以解释使用 ParentClass.apply（this）的重要性

Can anyonne explain the significance of using ParentClass.apply(this)

var CaffeineBeverage = function(){

};
var Coffee = function(){
    CaffeineBeverage.apply(this);
};
Coffee.prototype = new CaffeineBeverage();

PS：我试过评论CaffeineBeverage.apply（这个），但没有效果。以下是jsfiddle http://jsfiddle.net/pramodpv/8XqW9/ 的链接

PS: I tried commenting the CaffeineBeverage.apply(this), but no effect was there. Here is a link to jsfiddle http://jsfiddle.net/pramodpv/8XqW9/

推荐答案

它只是将父构造函数应用于正在构造的对象。尝试将一些东西添加到 CaffeineBeverage 构造函数中，你会看到我的意思。

It simply applies the parent constructor to the object being constructed. Try adding some stuff to the CaffeineBeverage constructor and you'll see what I mean.

var CaffeineBeverage = function(){
    this.tweakage = '123';
};

var Coffee = function(){
    CaffeineBeverage.apply(this);
};

不要这样做： Coffee.prototype = new CaffeineBeverage（）。改为：

Coffee.prototype = Object.create(CaffeineBeverage.prototype);

有关详细信息，请参阅这篇文章，它还为旧浏览器提供了一个垫片，它没有 Object.create 。

For more information on that, see this article, which also provides a shim for older browsers, which don't have Object.create.

测试出来：

var drink = new Coffee();
console.log(drink.tweakage); // 123

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