a.rb

# this directive processor enhances sprockets with the ability to load bower
# and npm packages
#
# usage is simple
#
# //= browserify 'my_library'
# window.MyLibrary
# browserify.modules['my_library']
#
# if you would like to to control the name of what's loaded do this
#
# //= browserify 'my_library' 'Foo'
# window.Foo
# browserify.modules['my_library']
#
# obviously you need to add you npm packages to sprockets' normal lookup path,
# something like this in middleman, and similar for rails
#
  module ::Sprockets
    module Browserify
      class DirectiveProcessor < ::Sprockets::DirectiveProcessor
        def process_browserify_directive(path, *args)
          name = args.shift || (File.basename(path).split('.').first)
          pathname = context.resolve(path)
          context.depend_on_asset(pathname)
          browserify_modules[name] = pathname
        end

        def browserify_modules
          @browserify_modules ||= Hash.new
        end

        def process_source
          super
        ensure
          browserify_modules.each do |name, pathname|
            @result << compile(name, pathname)
          end
        end

        def compile(name, pathname)
          pathname   = pathname.to_s
          id         = Browserify.identifier
          dirname    = test(?d, pathname) ? pathname : File.dirname(pathname)
          key        = File.basename(dirname)
          success    = false
          result     = nil

          cmd    = "PATH=./node_modules/.bin:$PATH browserify --standalone #{ id } #{ dirname }"
          result = `#{ cmd }`

          unless $?.exitstatus.zero?
            warn "#{ cmd } # FAILED"
            abort
          end

          <<-__
            // browserify: #{ dirname } ...
            //

            #{ result }
             
            this.browserify = this['browserify'] || {};

            this.browserify['modules'] = this.browserify['modules'] || {};

            this.browserify['modules'] = this.browserify['modules'] || {};

            this.browserify['modules']['#{ key }'] = this['#{ id }'];

            this['#{ name }'] = this.browserify['modules']['#{ key }'];

            //
            // browserify: #{ dirname } .
          __
        end

        def Browserify.identifier
          (@identifier ||= "@").succ!
        end
      end
    end
  end

  after_configuration do
    sprockets.unregister_processor('application/javascript', ::Sprockets::DirectiveProcessor)
    sprockets.register_processor('application/javascript', ::Sprockets::Browserify::DirectiveProcessor)
  end

# add bower modules to the sprockets asset path - load them with //= browserify 'package_name'
#
  after_configuration do
    @bower_config = JSON.parse(IO.read("#{root}/.bowerrc"))

    directory = File.join("#{root}", @bower_config["directory"])

    sprockets.append_path(directory)

    glob = File.join(directory, '*')

    Dir.glob(glob) do |entry|
      next unless test(?d, entry)
      sprockets.append_path(entry)
    end
  end

# add npm modules to the sprockets asset path - load them with //= browserify 'package_name'
#
  after_configuration do
    glob = File.join('node_modules', '*')

    Dir.glob(glob) do |entry|
      next unless test(?d, entry)
      sprockets.append_path(entry)
    end
  end

# let node (and browserify) know about packages we have installed in sprockets
#
  after_configuration do
    node_path = [sprockets.paths, (ENV['NODE_PATH'].split(':') if ENV['NODE_PATH'])].compact.flatten.join(':')
    ENV['NODE_PATH'] = node_path
  end