This topic covers integrating React.js with Rails using the Hyperloop gem
Other approaches not covered here are using the react-rails or react_on_rails gems.
Hyperloop will "prerender" the view server side so your initial view will load just like ERB or HAML templates. Once loaded on the client react takes over and will incrementally update the DOM as state changes due to inputs from the user, HTTP requests or incoming web socket data.
Besides Components, Hyperloop has Stores to manage shared state, Operations to encapsulate isomorphic business logic, and Models which give direct access to your ActiveRecord models on the client using the standard AR syntax.
More info here: http://ruby-hyperloop.io/