# File lib/generators/ember/generator_helpers.rb, line 47
      def engine_extension
        @engine_extension ||= begin
          extension_table = {
            'js' => 'js',
            'coffee' => 'coffee',
            'em' => 'em',
            'es6' => 'module.es6'
          }

          extension = extension_table[javascript_engine]

          raise "Unsupported javascript engine: `#{javascript_engine}` (Supported engines are: [#{extension_table.keys.join(', ')}])" if extension.nil?

          extension
        end
      end