JavaScript：.extend和.prototype用于什么？ [英] JavaScript: What are .extend and .prototype used for?

问题描述

我对JavaScript相对较新，并且继续在我使用的第三方库中看到.extend和.prototype。我认为它与Prototype javascript库有关，但我开始认为情况并非如此。这些用途是什么？

I am relatively new to JavaScript and keep seeing .extend and .prototype in third party libraries I am using. I thought it had to do with the Prototype javascript library, but I am beginning to think that is not the case. What are these used for?

推荐答案

Javascript的继承是基于原型的，所以你扩展了Date，Math等对象的原型。甚至你自己的自定义。

Javascript's inheritance is prototype based, so you extend the prototypes of objects such as Date, Math, and even your own custom ones.

Date.prototype.lol = function() {
 alert('hi');
};

( new Date ).lol() // alert message

In上面的代码片段，我为所有 Date对象（已经存在的对象和所有新对象）定义了一个方法。

In the snippet above, I define a method for all Date objects ( already existing ones and all new ones ).

extend 通常是一个高级函数，它复制你想要从中扩展的新子类的原型基类。

extend is usually a high level function that copies the prototype of a new subclass that you want to extend from the base class.

所以你可以这样做：

extend( Fighter, Human )

战斗机构造函数/对象将继承 Human 的原型，因此如果您定义 live 和 > 人类然后战斗机也将继承这些。

And the Fighter constructor/object will inherit the prototype of Human, so if you define methods such as live and die on Human then Fighter will also inherit those.

更新澄清：

高级函数意味着.extend不是内置的，但通常由jQuery等库提供或原型。

"high level function" meaning .extend isn't built-in but often provided by a library such as jQuery or Prototype.

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