css-optimizer

css-optimizer is a tool that helps you to remove un-used css rules (extra css rules) basing on sample html files of your website

Usage

//Step 01.
//Initialize CSSOptimizer with target css file (file will be optimized) 
//and output file (result file after optimizing target cssfile)
CSSOptimizer optimizer = new CSSOptimizer("bootstrap.css","bootstrap.min.css");

//Step 02. Sampling your website by downloading web pages or using http urls
optimizer.addHtmlFile("about-us.htm");
optimizer.addHtmlFile("home.htm");
optimizer.addHtmlFile("blog.htm");
optimizer.addHtmlFile("http://your-website.com/product/ipad");

//Step 03. Some classes or tags are added using Javascript code, declare them here:
optimizer.keepClassName("img-thumbnail");
optimizer.keepClassName("pagination");
optimizer.keepTagName("hr");
        
//Step 04. Execute optimizing, 
//result file will be stored in path that is declared in Step 01.
optimizer.optimize();

Example

We used css-optimizer to remove un-used css rules in library bootstrap.css.

As a result, 59% rule has been removed, css file size reduced from 121KB to 59KB and increased about 5 score when testing my site on Google PageSpeed

Please check out and run the test file TestCSSOptimizer.java to see example result

Solution and design

The most important things that i use in this project are Regular Expression and CSS Rule design. I use Regular Expression to split css rules and extract all information about rules and put them into object models (CSSStyleRule, NonCSSStyleRule and CSSMediaRule). Following is class diagram of css-optimizer:

Steps to optimize css file includes:

• Step 1. use jsoup to parse sampling html files and extract all used html tags and css classes
• Step 2. use Regular Expression to parse css file and put information into object models
• Step 3. compare the result from Step 1. and Step 2. to get only used css rules and write down them into the result file

Author and contact

ThoQ Luong

Email: thoqbk@gmail.com

License

The MIT License (MIT)