Smart Javascript Concatenation
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Fancycat concatenates JavaScript files in large web applications. It parties with Octocat

fancycat.rb is a script that reads our a list of template files and concatenates them up into one nice package, bearing in mind the best in DRY software. The goal of fancycat is to smartly concatenate a project's JS files based on how they are included in the HTML template files of any modern framework. This means the HTML file itself is the build script. No more maintaining separate build scripts. uses Varnish and ESIs, so we use the <esi:comment> tags to separate our the different final JS files we want packaged up.


<esi:comment text="Global.js" />
<script src="BLIP.js" />
<script src="BLIP/Object.js" />

<esi:comment text="Dashboard.js" />
<script src="Widget.js" />
<script src="Doodad.js" />

This example causes fancycat.rb to package the BLIP.js and Object.js files into a file called Global.js and Widget.js and Doodad.js into Dashboard.js. It is then recommended to minify this file using our standard YUI compressor or another minification tool.

Getting Started

Fancycat should be run on the commandline with your HTML templates as arguments. Example:

kelly% fancycat.rb templ/blipnew/template1.phtml templ/blipnew/template2.phtml uses Varnish and ESIs in our stack, so we delimit new comments using ESI comments. You could potentially use HTML comments, Rails templates comments or random strings if you feel like it. You will need to configure that yourself, though.

These comments tell Fancycat where to stop and start concatenating files.


Fancycat.rb is used by to concatenate their JavaScript for their large applications. Originally written by Kelly Sutton.