[翻译]High Performance JavaScript(012)
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 doesn't necessarily mean that it will run slowly. A lot of the performance impact is directly related to how the code has been organized and how you're attempting to solve a given problem.
代码整体结构是执行速度的决定因素之一。代码量少不一定运行速度快，代码量多也不一定运行速度慢。性能损失与代码组织方式和具体问题解决办法直接相关。
The techniques in this chapter aren't necessarily unique to JavaScript and are often taught as performance optimizations for other languages. There are some deviations from advice given for other languages, though, as there are many more JavaScript engines to deal with and their quirks need to be considered, but all of the techniques are based on prevailing computer science knowledge.
本章技术不仅适用于JavaScript也适用于其他语言的性能优化。还有一些为其他语言提供的建议，还要处理多种JavaScript引擎并考虑它们的差异，但这些技术都以当前计算机科学知识为基础。
Loops 循环
In most programming languages, the majority of code execution time is spent within loops. Looping over a series of values is one of the most frequently used patterns in programming and as such is also one of the areas where efforts to improve performance must be focused. Understanding the performance impact of loops in JavaScript is especially important, as infinite or long-running loops severely impact the overall user experience.
在大多数编程语言中，代码执行时间多数在循环中度过。在一系列编程模式中，循环是最常用的模式之一，因此也是提高性能必须关注的地区之一。理解JavaScript中循环对性能的影响至关重要，因为死循环或者长时间运行的循环会严重影响用户体验。
Types of Loops 循环的类�
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[转自]http://article.yeeyan.org/view/mouse4x/16540
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