You would just need to run a script that runs phantomjs (casperjs and you can run tests at the same time) and saves screenshots of different pages in your app.

You would just need to run a script that runs phantomjs (casperjs and you can run tests at the same time) and saves screenshots of different pages in your app. Then it checks in the images (possibly in a different repo that is just for comparing screenshots). This could be done as part of continuous integration. Whenever deploying one could generate a compare view with the last deployed revision.