gistfile1.rb

require 'sinatra/base'

module Sinatra
  module JavaScripts
      def js *scripts
        @js ||= []
        @js = scripts
      end

      def javascripts(*args)
        js = []
        js << settings.javascripts if settings.respond_to?('javascripts')
        js << args
        js << @js if @js
        js.flatten.uniq.map do |script| 
          "<script src=\"#{path_to script}\"></script>"
        end.join
      end

      def path_to script
        case script
          when :jquery then 'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js'
          when :rightjs then 'http://cdn.rightjs.org/right-2.3.0.js'
          when :backbone then 'http://cdnjs.cloudflare.com/ajax/libs/backbone.js/0.9.0/backbone-min.js'
          when :underscore then 'http://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.3.1/underscore-min.js'
          else script.to_s + '.js'
        end
      end
  end

  helpers JavaScripts
end