[翻译]High Performance JavaScript(026)
Use the Fast Parts 使用速度快的部分
Even though JavaScript is often blamed for being slow, there are parts of the language that are incredibly fast. This should come as no surprise, since JavaScript engines are built in lower-level languages and are therefore compiled. Though it's easy to blame the engine when JavaScript appears slow, the engine is typically the fastest part of the process; it's your code that is actually running slowly. There are parts of the engine that are much faster than others because they allow you to bypass the slow parts.
虽然JavaScript经常被指责缓慢，然而此语言的某些部分具有难以置信的快速。这不足为奇因为JavaScript引擎由低级语言构建。虽然JavaScript速度慢很容易被归咎于引擎，然而引擎通常是处理过程中最快的部分，实际上速度慢的是你的代码。引擎的某些部分比其它部分快很多，因为它们允许你绕过速度慢的部分。
Bitwise Operators 位操作运算符
Bitwise operators are one of the most frequently misunderstood aspects of JavaScript. General opinion is that developers don't understand how to use these operators and frequently mistake them for their Boolean equivalents. As a result, bitwise operators are used infrequently in JavaScript development, despite their advantages.
位操作运算符是JavaScript中经常被误解的内容之一。一般的看法是，开发者不知道如何使用这些操作符，经常在布尔表达式中误用。结果导致JavaScript开发中不常用位操作运算符，尽管它们具有优势。
JavaScript numbers are all stored in IEEE-754 64-bit format. For bitwise operations, though, the number is converted into a signed 32-bit representation. Each operator then works directly on this 32-bit representation to achieve a result. Despite the conversion, this process is incredibly fast when compared to other mathematical and Boolean operations in JavaScript.
JavaScript中的数字按照IEEE-754标准64位格式存储。在位运算中，数字被转换为有符号32位格式。每种操作均直接操作在这个32位数上�
相关文档：
typeof 是JavaScript的运算符
——返回一个用来表示表达式的数据类型的字符串
typeof[(] expression [)] //typeof语法中的圆括号是可选项
typeof 运算符@import url(../html-vss/msdnie4a.css);
typeof
运算符把类型信息当作字符串返回。typeof
返回值有� ......
AJAX (异步 JavaScript 和 XML) 是个新产生的术语,专为描述JavaScript的两项强大性能.这两项性
能在多年来一直被网络开发者所忽略,直到最近Gmail, Google suggest和google Maps的横空出世才使人
们开始意识到其重要性.
这两项被忽视的性能是:
* 无需重新装载整个页面便能向服务器发送请求.
* 对XML文档的解析和处理．
......
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 ......
A Note on Benchmarking 测试基准说明
Because a regex's performance can be wildly different depending on the text it's applied to, there's no straightforward way to benchmark regexes against each other. For the best result, you need to benchmark your regexes on test strings o ......
