middleman/middleman-core/lib/middleman-more/extensions/minify_javascript.rb

# Minify Javascript Extension
class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
  option :compressor, nil, 'Set the JS compressor to use.'
  option :inline, false, 'Whether to minify JS inline within HTML files'
  option :ignore, [], 'Patterns to avoid minifying'

  def initialize(app, options_hash={}, &block)
    super

    app.config.define_setting :js_compressor, nil, 'Set the JS compressor to use. Deprecated in favor of the :compressor option when activating :minify_js'
  end

  def after_configuration
    chosen_compressor = app.config[:js_compressor] || options[:compressor] || begin
      require 'uglifier'
      ::Uglifier.new
    end

    # Setup Rack middleware to minify CSS
    app.use Rack, :compressor => chosen_compressor,
                  :ignore     => Array(options[:ignore]) + [/\.min\./],
                  :inline     => options[:inline]
  end

  # Rack middleware to look for JS and compress it
  class Rack

    # Init
    # @param [Class] app
    # @param [Hash] options
    def initialize(app, options={})
      @app = app
      @compressor = options[:compressor]
      @ignore = options[:ignore]
      @inline = options[:inline]
    end

    # Rack interface
    # @param [Rack::Environmemt] env
    # @return [Array]
    def call(env)
      status, headers, response = @app.call(env)

      path = env["PATH_INFO"]

      begin
        if (path.end_with?('.html') || path.end_with?('.php')) && @inline
          uncompressed_source = ::Middleman::Util.extract_response_text(response)

          minified = uncompressed_source.gsub(/(<script[^>]*>\s*(?:\/\/(?:(?:<!--)|(?:<!\[CDATA\[))\n)?)(.*?)((?:(?:\n\s*)?\/\/(?:(?:-->)|(?:\]\]>)))?\s*<\/script>)/m) do |match|
            first = $1
            javascript = $2
            last = $3

            # Only compress script tags that contain JavaScript (as opposed
            # to something like jQuery templates, identified with a "text/html"
            # type.
            if first =~ /<script>/ || first.include?('text/javascript')
              minified_js = @compressor.compress(javascript)

              first << minified_js << last
            else
              match
            end
          end

          headers["Content-Length"] = ::Rack::Utils.bytesize(minified).to_s
          response = [minified]
        elsif path.end_with?('.js') && @ignore.none? {|ignore| Middleman::Util.path_match(ignore, path) }
          uncompressed_source = ::Middleman::Util.extract_response_text(response)
          minified_js = @compressor.compress(uncompressed_source)

          headers["Content-Length"] = ::Rack::Utils.bytesize(minified_js).to_s
          response = [minified_js]
        end
      rescue ExecJS::ProgramError => e
        warn "WARNING: Couldn't compress JavaScript in #{path}: #{e.message}"
      end

      [status, headers, response]
    end
  end
end