bundle install
rake db:migrate

Go to http://localhost:3000

Enter something in chat input box and press send. Nothing happens. If you look at the response from the server it's sending the opal javascript code back with a content-type of text/html; charset=utf-8.

Note that changing:

render type: :js, locals: { messages_html: render_to_string(@message) }

to:

render type: :js, content_type: 'application/javascript', locals: { messages_html: render_to_string(@message) }

makes it work by changing the response headers content-type to application/javascript; charset=utf-8.