[翻译]High Performance JavaScript(027)
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 with an empty cache (http://yuiblog.com/blog/2007/01/04/performance-research-part-2/). In addition, another more recent study by the Yahoo! Search team, which was independently confirmed by Steve Souders of Google, indicates that roughly 15% of the content delivered by large websites in the United States is served uncompressed.
根据Yahoo!卓越性能团队在2007年进行的研究，40%-60%的Yahoo!用户没有使用缓存的经验，大约20%页面视图不使用缓存（http://yuiblog.com/blog/2007/01/04/performance-research-part-2/）。另外，由Yahoo!研究小组发现，并由Google的Steve Souders所证实的一项最新研究表明，大约15%的美国大型网站所提供的内容没有压缩。
These facts emphasize the need to make sure that JavaScript-based web applications are delivered as efficiently as possible. While part of that work is done during the design and development cycles, the build and deployment phase is also essential and often overlooked. If care is not taken during this crucial phase, the performance of your application will suffer, no matter how much effort you've put into making it faster.
这些事实强调有必要确保那些基于JavaScript的网页应用尽量高效地发布。虽然部分工作在设计开发过程中已经完成，但构建和部署过程也很重要且往往被忽视。如果在这个关键过程中不够小心，你应用程序的性能将受到影响，无论你怎样努力使它更快。
The purpose of this chapter is to give you the necessary knowledge to efficiently assemble and deploy a JavaScript-based web application. A number of concepts are illustrated using Apache Ant, a Java-based build tool that has quickly become an industry standard for building applications for the Web. Toward the end of the chapter, a custo
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在函数体内定义的变量为局部变量，离开函数就挂掉了
在函数体内使用this.成员变量名，则为window对象级变量，即全局变量
故需要这样隐藏成员变量，向外只暴露get、set函数
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们开始意识到其重要性.
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