YUI Compressor

You can prevent specific local variables, nested functions, or function arguments from being obfuscated by placing a "hint" string at the very beginning of the function body. The hint is removed during compression.

Hint format: "argName:nomunge, localVar:nomunge, nestedFn:nomunge";

function fn (arg1, arg2, arg3) {
    "arg2:nomunge, localVar:nomunge, nestedFn:nomunge";

    ... 
    var localVar;
    ...

    function nestedFn () {
        ....
    }
}

To build the documentation locally, you need to install selleck globally, clone the repository, and then use selleck to output the documentation to a local pages directory. This process involves pulling the gh-pages branch and running the build command from the docs/ directory.

# Install the documentation builder
$ npm -g install selleck

# Clone the repository and a separate pages directory
$ git clone git://github.com/yui/yuicompressor.git
$ git clone git://github.com/yui/yuicompressor.git yuicompressor-pages

# Prepare the pages directory
cd yuicompressor-pages
git fetch
git checkout -t gh-pages

# Build the docs
cd ../yuicompressor/docs/
selleck -o ../../yuicompressor-pages/

You can use YUI Compressor within a Node.js application to compress files or strings asynchronously. Note that this package still requires Java to be installed on the system as it uses Java under the hood.

npm i yuicompressor

When using the Node.js API, you can pass the following options in the configuration object:

• charset: Character set to use (defaults to 'utf8').
• type: The type of compressor ('js' or 'css'; defaults to 'js').
• line-break: Specifies a column for line breaks.
• nomunge: If true, performs minification only without obfuscating local symbols.
• preserve-semi: Preserves unnecessary semicolons (e.g., before a }).
• disable-optimizations: Disables all built-in micro optimizations.

Import compressor from yuicompressor and call the compress method. The method accepts a file path or a string of JavaScript/CSS, an options object, and a callback function.

Callback arguments:

• err: Error object (contains stderr if an error occurs).
• data: The compressed string.
• extra: The stderr (contains warnings).

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
});

When calling compress or compressString, you can pass an options object to control the compression behavior. The following keys are supported:

• type: The type of file to compress (e.g., 'js' or 'css'). Defaults to 'js'.
• charset: The character encoding. Defaults to 'utf8'.
• line-break: Enables/disables line breaks.
• nomunge: Enables/disables variable renaming (munging).
• preserve-semi: Enables/disables semicolon preservation.
• disable-optimizations: Enables/disables optimizations.

The YUI Compressor CLI supports the following global options:

• -h, --help: Prints help documentation.
• --line-break <column>: Splits long lines after a specific column. Use 0 to break after each semicolon (JS) or rule (CSS).
• --type js|css: Specifies the compressor type. Required if no input file is provided or if the input file extension is not .js or .css.
• --charset <character-set>: Specifies the character set for reading and writing files.
• -o <outfile>: Specifies the output file. Supports filter syntax for multiple input files (e.g., -o '.css$:-min.css' *.css).
• -v, --verbose: Displays informational messages and warnings.

When compressing JavaScript, you can use these specific flags:

• --nomunge: Minify only; do not obfuscate local symbols.
• --preserve-semi: Preserve unnecessary semicolons (useful for tools like JSLint).
• --disable-optimizations: Disable all built-in micro optimizations.