Sinatra+Sprockets+DataMapper+CoffeeScript

app.js.coffee

//= require foo

document.write "<p>#{foo.f(10)}</p>"

app.rb

require 'sinatra'
require 'json'
require 'data_mapper'

DataMapper.setup(:default, 'sqlite::memory:')
DataMapper::Logger.new($stdout, :debug)

class Book
  include DataMapper::Resource

  property :id, Serial
  property :title, String, :required => true
  property :author, String, :required => true
end

DataMapper.auto_upgrade!

before do
  content_type :json
end

get '/books' do
  Book.all.to_json
end

post '/book' do
  newbook = Book.create(
    :title => params[:title],
    :author => params[:author]
  )
  { :id => newbook.id }.to_json
end

app_spec.rb

require './app'
require 'rspec'
require 'rack/test'

set :environment, :test

describe 'Book RESTful API' do
  include Rack::Test::Methods

  def app
    Sinatra::Application
  end

  it 'return book list' do
    post '/book', :title => 'hoge', :author => 'aaa'
    last_response.should be_ok
    p last_response.body

    get '/books'
    last_response.should be_ok
    p last_response.body
  end

end

config.ru

require './app'
require 'sprockets'
require 'coffee_script'

map '/assets' do
  env = Sprockets::Environment.new
  env.append_path 'assets/js'
  env.append_path 'assets/css'
  run env
end

map '/' do
  run Sinatra::Application
end

foo.js.coffee

foo = {}
foo.f = (x) -> num * 2 for num in [0..x]
window.foo = foo