guard-mozrepl

Make guard reload the current tab when things change.

Install

Install the awesome mozrepl extension, see...

https://github.com/bard/mozrepl/wiki

Don't forget to activate the Repl.

Tools → MozLab → Start MozRepl

Put this in your Gemfile

gem 'guard-mozrepl'

Run this

guard init mozrepl

...and you're all set.