Transparent coffeescript support for rails 3
Pull request Compare This branch is 111 commits behind Sutto:master.
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.


Barista is a rails plugin that transparently compiles CoffeeScript to JavaScript, by running the coffee compiler with Node.js. When a .coffee file is changed and the page is refreshed, it delays sending the .js file until it's been regenerated from the newly modified CoffeeScript. This way, you can refresh immediately after saving the .coffee file, and not worry about an old .js file being sent to the browser (as often happens when using coffee --watch).

Barista is very, very similar to bistro_car (infact, credit where credit is due - it shares similar code / is almost a fork).

The main difference being, it lets you use coffee as you would javascript. Simply put, Write coffee and place it in app/coffeescripts and Barista will automatically serve it as if it was placed in public/javascripts

That is, app/coffeescripts/ will work for /javascripts/demo.js. Even better (and more importantly for me), it provides Barista.compile_all! which takes all coffee files and compiles them into public/javascripts.

If you're using Jammit, this means you can simple run a rake task (rake barista:brew before running jammit) and your coffeescripts will be automatically provided, ready for bundling.

To add to your project, simply add:

gem 'barista', '>= 0.5.0'

To your Gemfile and run bundle install.

As you place .coffee files in app/coffeescripts, it will automatically handle them for you.

Please note that for Jammit compatibility etc, by default in test and dev mode it will automatically compile all coffeescripts that have changed before rendering the page.

Barista require rails 3+ (but patches for Rails 2 will be accepted.)


One of the other main features Barista adds (over bistro_car) is frameworks similar to Compass. The idea being, you add coffeescripts at runtime from gems etc. To do this, in your gem just have a coffeescript directory and then in you gem add the following code:

Barista::Framework.register 'name', 'full-path-to-directory' if defined?(Barista::Framework)

For an example of this in practice, check out bhm-google-maps or, the currently-in-development, shuriken. The biggest advantage of this is you can then manage js dependencies using existing tools like bundler.

In your Barista.configure block, you can also configure on a per-application basis the output directory for individual frameworks (e.g. put shuriken into vendor/shuriken, bhm-google-maps into vendor/bhm-google-maps):

Barista.configure do |c|
  c.change_output_prefix! 'shuriken',        'vendor/shuriken'
  c.change_output_prefix! 'bhm-google-maps', 'vendor/bhm-google-maps'

Alternatively, to prefix all, you can use Barista.each_framework (if you pass true, it includes the 'default' framework which is your application root).

Barista.configure do |c|
  c.each_framework do |framework|
    c.change_output_prefix!, "vendor/#{}"


Barista lets you hook into the compilation at several stages. Namely:

  • before compilation
  • after compilation
  • after compilation fails
  • after compilation complete

To hook into these hooks, you can use like so:

  • Barista.before_compilation { |path| puts "Barista: Compiling #{path}" }
  • Barista.on_compilation { |path| puts "Barista: Successfully compiled #{path}" }
  • Barista.on_compilation_with_warning { |path, output| puts "Barista: Compilation of #{path} had a warning:\n#{output}" }
  • Barista.on_compilation_error { |path, output| puts "Barista: Compilation of #{path} failed with:\n#{output}" }
  • Barista.on_compilation_complete { puts "Barista: Successfully compiled all files" }

These allow you to do things such as notify on compilation, automatically perform compression post compilation and a variety of other cool things.

An excellent example of these hooks in use is barista_growl, by Trevor Burnham - a gem perfect for development purposes that automatically shows growl messages on compilation.


Please note that barista lets you configure several options. To do this, it's as simple as setting up an initializer with:

rails generate barista_install

Then editing config/initializers/barista_config.rb.

Currently available options are:

  • root - the folder path to read coffeescripts from, defaults to app/coffeescripts
  • output_root - the folder to write them into, defautls to public/javascripts.
  • no_wrap - stop coffee from automatically wrapping JS in a closure.
  • change_output_prefix! - method to change the output prefix for a framework.

Note on Patches/Pull Requests

  1. Fork the project.
  2. Make your feature addition or bug fix.
  3. Add tests for it. This is important so I don't break it in a future version unintentionally.
  4. Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
  5. Send me a pull request. Bonus points for topic branches.


Copyright (c) 2010 Darcy Laycock. See LICENSE for details.