Make the API for compression consistent between JS and CSS. By defaul…

…t, users just need to say whether they want compression or not, and a default will be chosen by a Railtie. In the case of CSS, this default is already chosen by the sass-rails gem.

Users can still explicitly choose a compressor in their application.rb if they have a preference, but will usually want to let plugins choose defaults in their Railties.

actionpack/lib/sprockets/railtie.rb

@@ -30,7 +30,7 @@ def self.using_coffee?
 
       ActiveSupport.on_load(:action_view) do
         include ::Sprockets::Helpers::RailsHelper
-        
+
         app.assets.context_class.instance_eval do
           include ::Sprockets::Helpers::RailsHelper
         end
@@ -63,8 +63,12 @@ def asset_environment(app)
 
         env.logger = Rails.logger
 
-        env.js_compressor  = expand_js_compressor(assets.js_compressor)
-        env.css_compressor = expand_css_compressor(assets.css_compressor)
+        if assets.compress
+          # temporarily hardcode default JS compressor to uglify. Soon, it will work
+          # the same as SCSS, where a default plugin sets the default.
+          env.js_compressor  = expand_js_compressor(assets.js_compressor || :uglifier)
+          env.css_compressor = expand_css_compressor(assets.css_compressor)
+        end
 
         env
       end

railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt

@@ -14,9 +14,6 @@
   # Compress JavaScripts and CSS
   config.assets.compress = true
 
-  # Specify the default JavaScript compressor
-  config.assets.js_compressor  = :uglifier
-
   # Specifies the header that your server uses for sending files
   # (comment out if your front-end server doesn't support this)
   config.action_dispatch.x_sendfile_header = "X-Sendfile" # Use 'X-Accel-Redirect' for nginx