Session Check
A gem that supplies a JS routine to check every 10 sec to see if your session has expired, and boots you to the sign in page if it is.
Usage
Include the gem in your Gemfile…
gem 'session-check'
… and include the helper tag in your layout.erb, anywhere in the <head> tag.
<%= session_check %>
You’re done.
How it works
A JS timeout checks a value supplied from your Devise config, and when it determines that the Devise session has expired, it takes the user to the sign in page. A global AJAX listener ensures AJAX heavy apps are catered for, by listening to each request and resetting the counter for you.