Why do you want to use webruby over opal?
Webruby is now a gem!
Introducing mrubymix: static require for mruby
Webruby updates: the new optimization mode and minor API changes
Finally it's here: Webruby 1-2-3 tutorial
mruby irb now runs in a browser
It's official: mruby-browser is now called WebRuby!
Make mruby tests pass in a browser
Running mruby in a browser