There few issues here that should be looked at:
* the extension group should not be captured: you can do `\\(?:js\\|coffee\\)`
* the regex should capture also namespaced resources also, for example:
`app/assets/javascripts/foo/bar.js`
That means that here you need something similar to how the regex for controller is constructed:
`"app/assets/javascripts/\\(?:.+/\\)*\\(.+\\)\\.\\(?:js\\|coffee\\)$"`
* the extension could be something else then "js" or "coffee". What I would do here is to create `projectile-rails-js-extensions-re` variable and use it as `projectile-rails-views-re` [here](https://github.com/asok/projectile-rails/blob/master/projectile-rails.el#L278). If someone is using live script or some other extensions he could just append his extension to this variable.