現在的系統為了得到更好的用戶體驗，都加入了ajax的特效，只要用到了ajax的代碼，就會引來一大堆js代碼，這些代碼其實也挺占用帶寬的，為了使網 頁加載得更快，決定在項目中才用網上流行的js壓縮器來壓縮代碼。壓縮后的代碼基本可以抽掉40%左右的脂肪。

找到幾個壓縮器，發現很多壓縮器壓縮后的js代碼都出現這樣或那樣的問題

ESC 1.14 http://www.saltstorm.net/depo/esc/?pod=js 壓縮后有些中文會出現問號（我的js代碼是用utf-8格式）
jsmin http://www.crockford.com/javascript/jsmin.html 壓縮后有些中文會出現問號
dean edwards的packer http://dean.edwards.name/packer/ 壓縮后的js代碼會出現部分分號或大括號丟失，導致語法錯誤

最 后找到了yuicompressor-2.3.4 http://developer.yahoo.com/yui/compressor/ 感覺很好用，壓縮后無損代碼，而且連css也可以壓縮，壓縮的時候很多參數可以設置，可以制定js代碼的編碼格式等，java運行，本人寫了一個bat批 處理遍歷制定文件夾里面的所有js和css文件進行壓縮。

我自己寫的bat遍歷文件壓縮代碼



(dir %1 /aa /b /s | findstr /e /c:"js") >tmp.txt
for /f %%i in (tmp.txt) do java -jar yuicompressor-2.3.4.jar --type js --charset utf-8 -o %%i.tmp %%i & copy %%i".tmp" %%i & del %%i".tmp"


(dir %1 /aa /b /s | findstr /e /c:"css") >tmp.txt
for /f %%i in (tmp.txt) do java -jar yuicompressor-2.3.4.jar --type css --charset utf-8 -o %%i.tmp %%i & copy %%i".tmp" %%i & del %%i".tmp"


保存為 jscompressor.bat 運行的時候在輸入 jscompressor (是我們指定的路徑) 就可以批量進行壓縮，壓縮后替換壓縮前的代碼。



下面是一些參數的說明。

==============================================================================
YUI Compressor
==============================================================================

NAME

YUI Compressor - The Yahoo! JavaScript and CSS Compressor

SYNOPSIS

Usage: java -jar yuicompressor-x.y.z.jar [options] [input file]

Global Options
-h, --help Displays this information
--type Specifies the type of the input file
--charset Read the input file using
--line-break Insert a line break after the specified column number
-v, --verbose Display informational messages and warnings
-o Place the output into . Defaults to stdout.

JavaScript Options
--nomunge Minify only, do not obfuscate
--preserve-semi Preserve all semicolons
--disable-optimizations Disable all micro optimizations

DESCRIPTION

The YUI Compressor is a JavaScript compressor which, in addition to removing
comments and white-spaces, obfuscates local variables using the smallest
possible variable name. This obfuscation is safe, even when using constructs
such as 'eval' or 'with' (although the compression is not optimal is those
cases) Compared to jsmin, the average savings is around 20%.

The YUI Compressor is also able to safely compress CSS files. The decision
on which compressor is being used is made on the file extension (js or css)

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.

-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.