Javascript expando对象 [英] Javascript expando objects

问题描述

javascripts中的expando对象是什么？

What are expando objects in javascripts?

出于什么目的我们需要这个？任何完整的例子将不胜感激

For what purpose we need this ? Any complete example will be appreciated

我在这里找到了一篇文章 Javascript：网络开发的红头发的继子女

I found 1 article here Javascript: The red-headed stepchild of web development

推荐答案

嗯，在javascript中，任何对象都是一个expando对象。正如文章所述，这意味着每当您尝试访问属性 ¹ 时，它将自动生成。

Well, in javascript, any object is an expando object. What it means is, as the article covers, that whenever you try to access a property¹ it will automatically be created.

var myObj = {}; // completely empty object
myObj.myProp = 'value';

当您指定 myProp 一个值时，属性 myProp 是动态创建的，尽管它之前不存在。在许多其他语言中，例如C＃，这通常是不可能的（实际上C＃也刚刚启用了expando对象支持，但除此之外）。要在C＃中访问普通类中的属性，您需要在类中指定它确实具有此属性。

The moment you assign myProp a value, the property myProp is dynamically created, eventhough it didn't exist before. In a lot of other languages, such as C#, this is not normally possible (actually C# has just enabled expando object support as well, but that's besides the point). To access a property in a normal class in C#, you need to specify in the class that it does indeed have this property.

¹ 不非常正确。请参阅下面的npup评论以获得澄清。

¹ Not quite correct. See npup's comment below for clarification.

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