[翻译]High Performance JavaScript(031)
Firebug
Firefox is a popular browser with developers, partially due to the Firebug addon (available at http://www.getfirebug.com/), which was developed initially by Joe Hewitt and is now maintained by the Mozilla Foundation. This tool has increased the productivity of web developers worldwide by providing insights into code that were never before possible.
对开发人员来说，Firefox是一个时髦的浏览器，部分原因是Firebug插件（http://www.getfirebug.com/）由Joe Hewitt首创现在由Mozilla基金会维护。此工具具有前所未有的代码洞察力，提高了全世界网页开发者的生产力。
Firebug provides a console for logging output, a traversable DOM tree of the current page, style information, the ability to introspect DOM and JavaScript objects, and more. It also includes a profiler and network analyzer, which will be the focus of this section. Firebug is also highly extensible, enabling custom panels to be easily added.
Firebug提供了一个控制台日志输出，当前页面的DOM树显示，样式信息，能够反观DOM和JavaScript对象，以及更多功能。它还包括一个性能和网络分析器，这是本节的重点。Firebug易于扩展，可添加自定义面板。
Console Panel Profiler 控制台面板分析器
The Firebug Profiler is available as part of the Console panel (see Figure 10-1). It measures and reports on the execution of JavaScript on the page. The report details each function that is called while the profiler is running, providing highly accurate performance data and valuable insights into what may be causing scripts to run slowly.
Firebug分析器是控制台面板的一部分（如图10-1）。它测量并报告页面中运行的JavaScript。当分析器运行时，报告深入到每个被调用函数的细节，提供高精确的性能数据和变量察看功能，（有助于）找出可能导致脚本运行变慢的原因。
Figure 10-1. FireBug Console panel
图 10-1 FireBug控制台面板
One way to run a profile is by clicking the Profile button, triggering the script, and clicking the P
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本文主要是出于有朋友使用我原来写的autocomplete的JS控件。当数据量大的时候，会出现效率极其慢的情况，我在这段时间做出的一些测试也及一些经验，与大家分享，如果有错的地方，还请指出。
经过测试，我们会发现如下的情况或者说的结论，如果您的测试结果与我的不符，请说明原因，以便相互学习。
1）当一个较大的HTML字� ......
function total(){
var i=0;
for(j=1;j<=20;j++)
{
var step="step"+j;
if(document.getElementById(step)){
if(document.getElementById(step).checked==true)
{
i=i+parseInt(document.getElementById(step).value);
}
}
}
document.getElementById("total").innerHTML = i;
}
function Resetvalue(){
......
第五章 Strings and Regular Expressions 字符串和正则表达式
Practically all JavaScript programs are intimately tied to strings. For example, many applications use Ajax to fetch strings from a server, convert those strings into more easily usable JavaScript objects, and ......
第九章
Building and Deploying High-Performance JavaScript Applications
创建并部署高性能JavaScript应用程序
According to a 2007 study by Yahoo!'s Exceptional Performance team, 40%–60% of Yahoo!'s users have an empty cache experience, and about 20% of all page views are done ......
JavaScript Minification JavaScript紧凑
JavaScript minification is the process by which a JavaScript file is stripped of everything that does not contribute to its execution. This includes comments and unnecessary whitespace. The process typically reduces the file size by ha ......
