title: Rails 4 default respond_to for ajax controller
body: <p>I have a rails controller where every action has the same respond_to block for every action, eg:</p>
  
  <pre><code>def some_action
    respond_to do |format|
      format.html { redirect_to :back }
      format.js   { render layout: false }
    end
  end 
  </code></pre>
  
  <p>Is there a way that I can set this as the default response for all actions? I know that I can use </p>
  
  <pre><code>respond_to :html, :js
  </code></pre>
  
  <p>at the top of the  controller, but can this be used to set the specific responses for each format?</p>