Rails 3.1 introduced the asset pipeline, which make it easy to include versioned external assets as application dependencies.

Probably you will find almost any JS library you want, already Gemified, but, if it is not the case, you can Gemify those libraries by your own, and I can help you with it. So, let’s do it!

1. Create the project skeleton

Bundler makes it simple to create the files and folders necessary for building a Gem:

$ bundle gem somelibrary

This command will create basically the following tree:

$ tree
├── Gemfile
├── lib
│   ├── somelibrary
│   │   └── version.rb
│   └── somelibrary.rb
├── LICENSE.txt
├── Rakefile
├── README.md
└── somelibrary.gemspec

But, I usually made some changes to it:

1. Delete the version.rb file and it’s parent folder:

$ rm -rf lib/somelibrary

Heads up: Don’t forget to change the lib/someligrary.rb and somelibrary.gemspec files!

2. As I said in item 1, change the somelibrary.gemspec file…

Remove the references to version.rb, put a static version, replace the TODO’s by your own texts.

3. As I said in item 1, change the lib/somelibrary.rb file…

You had to force it to load the rails engine:

module Somelibrary
    class Engine < ::Rails::Engine

2. Create the vendor/assets folder

That’s easy!

$ mkdir -p vendor/assets/{javascripts,stylesheets}

3. Copy the assets to the folders

Even easier, just copy the respective js and css files to javascripts and stylesheets folders, respectively.

4. Test

Now, create some rails app, and add the following to the Gemfile:

gem 'somelibrary', path: 'absolute/path/to/your/gem'

And, off course, add the respective imports in your application.js and application.css files.

5. Document

Yeah, users would like some documentation and a few appointments about how to use your Gem. So, please, do it.

6. Release

Well, now that the Gem is crafted, tested and documented, we could finally release it.

Create a github repository for your gem, and do the basics:

$ git init
$ git add -A
$ git commit -m 'first'
$ git remote add https://github.com/USER/REPO
$ git push origin master

And then, finally, release it using Rake:

$ rake release

This will create a tag for the version specified in your gemspec, push it to github and to rubygems.org.

Simple, uh?

7. Enjoy

Now, just use it as a normal gem :)

Hope you enjoyed the post.