Opal Stimulus for Rails

Opal Stimulus is a Stimulus wrapper made with Opal (a source-to-source Ruby to JavaScript compiler) that allows you to write Stimulus controllers in Ruby instead of JavaScript (It works only with Rails).

Installation

Add this line to your Gemfile:

gem 'opal_stimulus'

Execute:

bundle install
rails generate opal_stimulus:install

Start application:

bin/dev

Basic Example

Here's a Hello World example with OpalStimulus. Compare with the original JavaScript example:

Ruby Controller:

# app/opal/controllers/hello_controller.rb
# new controllers will be automatically added to app/opal/controllers_requires.rb
#   (ordered files load is not supported yet)
class HelloController < StimulusController
  self.targets = ["name", "output"]

  def greet
    output_target.content = "Hello, #{name_target.value}!"
  end
end

HTML:

<div data-controller="hello">
  <input data-hello-target="name" type="text">

  <button data-action="click->hello#greet">
    Greet
  </button>

  <span data-hello-target="output">
  </span>
</div>

Result

Screen.Recording.2025-06-19.at.11.19.18.mov

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/josephschito/opal_stimulus.

License

The gem is available as open source under the terms of the MIT License.