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Rack::Sprocketize

Rack::Sprocketize is a piece of Rack Middleware which uses Sprockets to concatenate javascript files and then optionally compresses them. In a development environment, the files will be sprocketized on each request if there have been changes to the source files. In a production environment, the files will only be sprocketized one time, and only if there have been changes. Also, in a production environment, the files will be compressed by whichever javascript compressor is available.

Installation

$ gem install rack-sprocketize

Basic Usage

In a Rack based app, use Rack::Sprocketize just like any other middleware, passing options if necessary.

require 'rack-sprocketize'
use Rack::Sprocketize, :always_compress => true

In a Rails 3 app, Rack::Sprocketize is automatically included in the middleware stack, so all you need to worry about is configuration.

# Gemfile
gem 'rack-sprocketize'

# config/application.rb
config.sprocketize.always_compress = true

Sprocketizing

Rack::Sprocketize takes each file in the given :source_path ('app/javascripts' by default) and uses Sprockets to include any other required files. Then it outputs the results in the :output_path ('public/javascripts by default). Also, files that begin with '_' will not be sprocketized and will essentially be treated like partials.

So, given the following files in an app:

// app/javascripts/main.js
//= require "_partial"

// app/javascripts/_partial.js
var hello = 'world';

// app/javascripts/plugin.js
var plugin = 'blah';

Rack::Sprocketize will sprocketize them into :output_path like this:

// public/javascripts/main.js
var hello = 'world';

// public/javascripts/plugin.js
var plugin = 'blah';

Notice how the files weren't all concatenated into one file. You use Sprockets' //= require syntax to control how the files will be concatenated.

Both the :source_path and :output_path can be customized when setting up Rack::Sprocketize:

use Rack::Sprocketize, :source_path => 'js', :output_path => 'public/js'

Compression

Rack::Sprocketize determines which javascript compressor you want to use based on which one has been required.

require 'packr'
use Rack::Sprocketize
# would use Packr

or in Rails:

# Gemfile
gem 'jsmin'

# config/application.rb
config.middleware.use Rack::Sprocketize
# would use JSMin

To pass options to the javascript compressor just use the :compression_options option:

require 'packr'
use Rack::Sprocketize, :compression_options => { :shrink_vars => true }

By default, the files are only compressed in a production environment. If for some reason you want them to always be compressed, pass the :always_compress option:

use Rack::Sprocketize, :always_compress => true