I am using the rails-backbone gem ( https://github.com/codebrew/backbone-rails). For rendering HTML, it uses some kind of javascript templates, whose name I cannot tell even aft
Rails processes EJS templates with ejs gem which is a port of underscore.js's _.template function to Ruby. Output of that is a javascript function which in turn will produce the html when run in the browser.
Here's recent article which includes also description of backbone-rails: