This was from the Vert.x template project and can be built with Maven.
It is an adaptation of the ReactJS tutorial project that is adapted to work with a Vert.x (in Ruby) backend.
It may not be very good.
The meat of the project is in
src/main/resources/web_server_verticle.rb
and
src/main/resources/web/index.html
It can be run with
mvn package vertx:runMod