[翻译]High Performance JavaScript(016)
Regular Expression Optimization 正则表达式优化
Incautiously crafted regexes can be a major performance bottleneck (the upcoming section, "Runaway Backtracking" on page 91, contains several examples showing how severe this can be), but there is a lot you can do to improve regex efficiency. Just because two regexes match the same text doesn't mean they do so at the same speed.
粗浅地编写正则表达式是造成性能瓶颈的主要原因（后面“回溯失控”一节有一些例子说明这是多么严重的问题），但还有很多可以改进正则表达式效率的地方。两个正则表达式匹配相同的文本并不意味着他们具有同等的速度。
Many factors affect a regex's efficiency. For starters, the text a regex is applied to makes a big difference because regexes spend more time on partial matches than obvious nonmatches. Each browser's regex engine also has different internal optimizations.
许多因素影响正则表达式的效率。首先，正则表达式适配的文本千差万别，部分匹配时比完全不匹配所用的时间要长。每种浏览器的正则表达式引擎也有不同的内部优化。
Regex optimization is a fairly broad and nuanced topic. There's only so much that can be covered in this section, but what's included should put you well on your way to understanding the kinds of issues that affect regex performance and mastering the art of crafting efficient regexes.
正则表达式的优化是一个相当广泛和细致入微的话题。本节讨论尽其所能，希望这些内容有助于您理解影响正则表达式性能的各种问题和掌握编写高效正则表达式的艺术。
Note that this section assumes you already have some experience with regular expressions and are primarily interested in how to make them faster. If you're new to regular expressions or need to brush up on the basics, numerous resources are available on the Web and in print. Regular Expressions Cookbook (O'Reilly) by Jan Goyvaerts and Steven Levithan (that's me!) is written for people who like to learn by doing, and
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面向对象的语言多数都支持继承，继承最重要的优点就是代码复用，从而构建大型软件系统。如果一个类能够重用另一个类的属性和或方法，就称之为继承。
从这个角度来看看js的继承方式。js中继承方式与写类方式息息相关。不同的写类方式造成不同的继承方式。各种流行js库继承方式也各不相同。从最简单的
复用开始。
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第四章 Algorithms and Flow Control 算法和流程控制
The overall structure of your code is one of the main determinants as to how fast it will execute. Having a very small amount of code doesn't necessarily mean that it will run quickly, and having a large amount of code ......
Conditionals 条件表达式
Similar in nature to loops, conditionals determine how execution flows through JavaScript. The traditional argument of whether to use if-else statements or a switch statement applies to JavaScript just as it does to other languages. Since different b ......
Recursion Patterns 递归模式
When you run into a call stack size limit, your first step should be to identify any instances of recursion in the code. To that end, there are two recursive patterns to be aware of. The first is the straightforward recursive pattern represented ......
