Remove unused styles from CSS

npm install -g uncss

var uncss = require('uncss');

var files   = ['my', 'array', 'of', 'HTML', 'files'],
    options = {
        ignore: ['#added_at_runtime', /test\-[0-9]+/],
        csspath: "../public/css/",
        raw: 'h1 { color: green }',
        stylesheets: ["lib/bootstrap/dist/css/bootstrap.css", "src/public/css/main.css"],
        urls: ["http://localhost:3000/mypage", "..."] //array of urls
        timeout: 1000
    };

uncss(files, options, function (output) {
    console.log(output);
});

/* Look Ma, no options! */
uncss(files, function (output) {
    console.log(output);
});

/* Specifying raw HTML*/
var raw_html = '...'
uncss(raw_html, options, function (output) {
    console.log(output);
});

Usage: uncss [options] <file ...>

Options:

-h, --help                     output usage information
-V, --version                  output the version number
-i, --ignore <selector, ...>   Do not remove given selectors
-C, --csspath <path>           Relative path where the CSS files are located
-s, --stylesheets <file, ...>  Specify additional stylesheets to process
-r, --raw <string>             Pass in a raw string of CSS
-t, --timeout <milliseconds>   Wait for JS evaluation

UnCSS can also be used in conjunction with other javascript build systems, thanks to @addyosmani for creating:

• grunt-uncss
• gulp-uncss-task

• ignore [Array]: provide a list of selectors that should not be removed by UnCSS. For example, styles added by user interaction with the page (hover, click), since those are not detectable by UnCSS yet. Both literal names and regex patterns are recognized.
• csspath [String]: Path where the CSS files are related to the html files. By default, UnCSS uses the path specified in the <link rel="stylesheet" href="path/to/file.css">
• stylesheets [Array]: Force the list of stylesheets to optimize using a path relative to the Gruntfile.js. Otherwise, it extracts the stylesheets from the html files.
• raw [String]: Give the task a raw string of CSS in addition to the existing stylesheet options; useful in scripting when your CSS hasn't yet been written to disk.
• urls [Array]: Array of URLs to load with Phantom (on top of the files already passed if any).
• timeout [Number]: Specify how long to wait for the JS to be loaded.

Copyright (c) 2013 Giacomo Martino. See the LICENSE file for license rights and limitations (MIT).

• Fully support all CSS selectors
• Support @-rules