Ruby2JS

Minimal yet extensible Ruby to JavaScript conversion.

Documentation | Live Demo

Installation

# Gemfile
gem 'ruby2js'

Or install directly:

gem install ruby2js

Examples

Ruby2JS converts Ruby syntax to clean, readable JavaScript:

# Ruby                              # JavaScript
a = { age: 3 }                      # let a = {age: 3}
a.age += 1                          # a.age++

items.map { |x| x * 2 }             # items.map(x => x * 2)

class Dog < Animal                  # class Dog extends Animal {
  def bark                          #   bark() {
    puts "woof!"                    #     console.log("woof!")
  end                               #   }
end                                 # }

Quick Start

require 'ruby2js'

puts Ruby2JS.convert("a = {age: 3}; a.age += 1", preset: true)
# => let a = {age: 3}; a.age++

Command Line

ruby2js --preset file.rb
echo "puts 'hello'" | ruby2js --preset

Features

• Filters - Transform Ruby methods to JavaScript equivalents (e.g., .each → .forEach)
• ES Level Support - Target specific JavaScript versions (ES5 through ES2022+)
• Framework Integrations - Rails, Stimulus, React, Lit, and more
• Live Demo - Try it in your browser (runs entirely client-side via Opal)

Contributing

Running Tests

bundle install
bundle exec rake test_all

Running the Website Locally

The ruby2js.com website (including the live demo) can be run locally from the docs folder:

cd docs
bundle install
yarn install
bundle exec rake            # build demo assets (Opal-compiled ruby2js, etc.)
bin/bridgetown start        # run the site's dev server

The site will be available at http://localhost:4000.

Release Process for Maintainers

1. Update the version in both packages/ruby2js/package.json and lib/ruby2js/version, ensuring they match.
2. Run bundle exec rake release_core

License

MIT License - Copyright (c) 2009, 2025 Macario Ortega, Sam Ruby, Jared White

See LICENSE for details.