YUI Compressor 是一个用来压缩 JS 和 CSS 文件的工具，采用Java开发。
使用方法：
//压缩JS
java -jar yuicompressor-2.4.2.jar --type js --charset utf-8 -v src.js > packed.js
//压缩CSS
java -jar yuicompressor-2.4.2.jar --type css --charset utf-8 -v src.css > packed.css
How does the YUI Compressor work?
The YUI Compressor is written in Java (requires Java >= 1.4) and relies on Rhino to tokenize the source JavaScript file. It starts by analyzing the source JavaScript file to understand how it is structured. It then prints out the token stream, omitting as many white space characters as possible, and replacing all local symbols by a 1 (or 2, or 3) letter symbol wherever such a substitution is appropriate (in the face of evil features such as eval or with, the YUI Compressor takes a defensive approach by not obfuscating any of the scopes containing the evil statement) The CSS compression algorithm uses a set of finely tuned regular expressions to compress the source CSS file. The YUI Compressor is open-source, so don't hesitate to look at the code to understand exactly how it works.
Using the YUI Compressor from the command line
$ java -jar yuicompressor-x.y.z.jar Usage: java -jar yuicompressor-x.y.z.jar [options] [input file] Global Options -h, --help Displays this information --type <js|css> Specifies the type of the input file --charset <charset> Read the input file using <charset> --line-break <column> Insert a line break after the specified column number -v, --verbose Display informational messages and warnings -o <file> Place the output into <file> or a file pattern. Defaults to stdout. JavaScript Options --nomunge Minify only, do not obfuscate --preserve-semi Preserve all semicolons --disable-optimizations Disable all micro optimizations GLOBAL OPTIONS -h, --help Prints help on how to use the YUI Compressor --line-break Some source control tools don't like files containing lines longer than, say 8000 characters. The linebreak option is used in that case to split long lines after a specific column. It can also be used to make the code more readable, easier to debug (especially with the MS Script Debugger) Specify 0 to get a line break after each semi-colon in JavaScript, and after each rule in CSS. --type js|css The type of compressor (JavaScript or CSS) is chosen based on the extension of the input file name (.js or .css) This option is required if no input file has been specified. Otherwise, this option is only required if the input file extension is neither 'js' nor 'css'. --charset character-set If a supported character set is specified, the YUI Compressor will use it to read the input file. Otherwise, it will assume that the platform's default character set is being used. The output file is encoded using the same character set. -o outfile Place output in file outfile. If not specified, the YUI Compressor will default to the standard output, which you can redirect to a file. Supports a filter syntax for expressing the output pattern when there are multiple input files. ex: java -jar yuicompressor.jar -o '.css$:-min.css' *.css ... will minify all .css files and save them as -min.css -v, --verbose Display informational messages and warnings. JAVASCRIPT ONLY OPTIONS --nomunge Minify only. Do not obfuscate local symbols. --preserve-semi Preserve unnecessary semicolons (such as right before a '}') This option is useful when compressed code has to be run through JSLint (which is the case of YUI for example) --disable-optimizations Disable all the built-in micro optimizations.