全局变量有什么不好？ [英] What is so bad about global variables?

问题描述

可能重复：

在JavaScript圣经中，据说全局变量（不带var关键字的变量）是一件非常糟糕的事情。好吧，与强类型语言比如Java或C ++相比，JavaScript就像街头流氓俚语（was！）。

但是有没有任何性能问题？或者它导致浏览器崩溃？或者在使用全局变量时有一些明显的差异？

我学习了JavaScript，并遵循书籍和专家的指导原则，但是知道为什么这是一个非常重要的主题。

解决方案

如果采用良好的结构化方法，全局变量完全可以接受使用，并实际上节省了一些开销与所有传递/复制各种指针/变量。

对我来说，使用本地变量更多的是它的容易程度维护，调试和移植到其他系统的代码。

Possible Duplicate:
Why is it bad to make elements global variables in Javascript?

In the JavaScript bible, it is said that global variables (variables declared without the "var" keyword) are a very bad thing. Ok, comparing to strongly typed languages like Java or C++ JavaScript is like a street gang slang (was!).

But are there any performance problems? Or is it causing the browser to crash? Or are there some actual noticeable difference when using globals?

I have learned JavaScript on my own and I follow the guidelines of the books and experts, but it will be nice to know why this is such an important subject.

解决方案

If one takes a good structured approach, global variables are perfectly acceptable to use, and actually save a bit of overhead with all the passing around / copying of various pointers / variables.

For me, using local vars is more a matter of how easy it makes the code to maintain, debug, and port to other systems.

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