yuicompressor java_yuicompressor

YUI Compressor – The Yahoo! JavaScript and CSS Compressor

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 in 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)

Building

ant

Testing

./tests/suite.sh

Node.js Package

You can require compressor in a Node.js package and compress files and strings in async.

It still uses Java under the hood

npm i yuicompressor

var compressor = require(‘yuicompressor’);

compressor.compress(‘/path/to/file or String of JS’, {

//Compressor Options:

charset: ‘utf8’,

type: ‘js’,

nomunge: true,

‘line-break’: 80

}, function(err, data, extra) {

//err If compressor encounters an error, it’s stderr will be here

//data The compressed string, you write it out where you want it

//extra The stderr (warnings are printed here in case you want to echo them

});

Options:

charset // defaults to ‘utf8’

type // defaults to ‘js’

line-break

nomunge

preserve-semi

disable-optimizations

TODO

Better Docs

Help Pages

Build Status

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.

Notes

If no input file is specified, it defaults to stdin.

Supports wildcards for specifying multiple input files.

The YUI Compressor requires Java version >= 1.5.

It is possible to prevent a local variable, nested function or function

argument from being obfuscated by using “hints”. A hint is a string that

is located at the very beginning of a function body like so:

function fn (arg1, arg2, arg3) {

“arg2:nomunge, localVar:nomunge, nestedFn:nomunge”;

…

var localVar;

…

function nestedFn () {

….

}

…

}

The hint itself disappears from the compressed file.

C-style comments starting with /*! are preserved. This is useful with

comments containing copyright/license information. As of 2.4.8, the ‘!’

is no longer dropped by YUICompressor. For example:

/*!

* TERMS OF USE – EASING EQUATIONS

* Open source under the BSD License.

* Copyright 2001 Robert Penner All rights reserved.

*/

remains in the output, untouched by YUICompressor.

Modified Rhino Files

YUI Compressor uses a modified version of the Rhino library

(http://www.mozilla.org/rhino/) The changes were made to support

JScript conditional comments, preserved comments, unescaped slash

characters in regular expressions, and to allow for the optimization

of escaped quotes in string literals.

Copyright And License

Copyright (c) 2013 Yahoo! Inc. All rights reserved.

The copyrights embodied in the content of this file are licensed

by Yahoo! Inc. under the BSD (revised) open source license.