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Some brief instructions on how to use Sprocket 2 in Rails to get CoffeeScript
powered JS and SASS powered CSS with YUI compression all via the magic of rack.
This stuff will be native in Rails 3.1 and the layout of the files on the
filesystem will be different but this guide will get you working with it
while we wait for all that to finalize.
Ignore the number prefixes on each file. This is just to ensure proper order in the Gist.
It's based on eric1234 gist ijust made it 3.1 compliant in terms of convention
if defined?(Bundler)
# If you precompile assets before deploying to production,
use this line
Bundler.require *Rails.groups(:assets => %w(development test))
# If you want your assets lazily compiled in production,
use this line
# Bundler.require(:default, :assets, Rails.env)
group :assets do
gem 'coffee-script'
gem 'yui-compressor', :require => 'yui/compressor'
gem 'sass'
gem 'sass-rails'
gem 'sprockets', :git => 'git://'
gem "therubyracer"
# better than subclassing Sprockets::Environment according to Josh
Assets = do |env|
assets = ["javascripts", "stylesheets", "images", "fonts"]
paths = ["app/assets/", "lib/assets/", "vendor/assets/" ].map{|path|{|folder| "#{path}#{folder}" } }.flatten
paths.each{ |path| env.append_path path }
if Rails.env.staging? || Rails.env.production?
env.js_compressor = :munge => true, :optimize => true
env.css_compressor =
# Mount the rack end-point for JavaScript and CSS.
MyApp::Application.routes.draw do
# Add this line
mount Assets => '/assets'
# Put this in your app/assets/javascripts/application.js directory and call /assets/application.js in your browser
# You need to have jquery and jquery_ujs files (jquery_ujs is sometimes named rails.js)
# In your layout just add
# <%= javascript_include_tag "/assets/application" %>
# In Rails 3.1 you could even do
# <%= javascript_include_tag "application" %>
//= require jquery
//= require jquery_ujs
//= require_tree .
# Put this in your app/assets/javascripts directory, it will be included when you call /assets/application.js in your browser
alert 'hello world'
// Put this in your app/assets/stylesheets directory and call /assets/application.css in your browser
// In your layout just add
// <%= stylesheet_link_tag "/assets/application" %>
// In Rails 3.1 you could even do
// <%= stylesheet_link_tag "application" %>
*= require_tree .
// Put this in your app/assets/stylesheets directory and call /assets/application.css in your browser
body {margin: 2px + 5px}
Sprockets 2 has a lot more under the hood but this gets you started.
A few things not covered:
1. Anything supported by Tilt can be used as a template engine
(not just Sass and CoffeeScript).
2. Although Sass has native abilities to include other files, Sprockets 2
gives the ability to all formats through special comments like:
// =require "foo"
It's special commands can be fairly powerful (like requiring an entire
directory or tree). NOTE: Use the comment character relevant for the
language. So coffescript should be:
# =require 'foo.js'
Then you can create '' and when served it will be as one
3. Sprockets 2 has the ability to pre-compile the assets for maximum speed.
Also useful when the deployment environment doesn't support a template
language (like CoffeeScript).
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