This version uses nothing but the Rails asset pipeline, plain ES5 JavaScript, and the jQuery that ships with Rails.

Just launch Rails normally:

rails server

• Zero setup: just create a new JS file and get minification and gzipping out of the box
• Plain ES5: no Babel or CoffeeScript required, though CoffeeScript support also comes out of the box
• Progressive: The parts of the app that have to be smart are, but everything else is just regular HTML
• Scoped: all classes begin with js-, so that both developers and designers can happily add and remove classes without accidentally stepping on each other's toes
• jQuery UJS: Rails' builtin jQuery UJS automatically sends the authenticity token in the header of jQuery's web requests

• Too imperative: jQuery-style programming is inherently imperative, which doesn't work well with the more functional reactivity model that makes UIs easy to think about
• Componentization is hard: The patterns to manage state, declarative rendering, events, actions, etc all require discipline and experience
• Lots of boilerplate: A lot of extra classes and extra code, which would require reinventing a framework to DRY up
• Ugly HTML: No HTML syntax highlighting and it must be built using clunky string concatenation