Reactrb / Reactive-Ruby

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Reactrb is an Opal Ruby wrapper of React.js library.

It lets you write reactive UI components, with Ruby's elegance using the tried and true React.js engine. :heart:

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Important: react.rb and reactive-ruby gems are deprecated. Please read this!


Install the gem, or load the js library

  • add gem 'reactrb' to your gem file or
  • gem install reactrb or
  • install (or load via cdn) reactrb-express.js

For gem installation it is highly recommended to read the getting started and installation guides at

Quick Overview

Reactrb components are ruby classes that inherit from React::Component::Base or include React::Component.

React::Component provides a complete DSL to generate html and event handlers, and has full set of class macros to define states, parameters, and lifecycle callbacks.

Each react component class has a render method that generates the markup for that component.

Each react component class defines a new tag-method in the DSL that works just like built-in html tags, so react components can render other react components.

As events occur, components update their state, which causes them to rerender, and perhaps pass new parameters to lower level components, thus causing them to rerender.

Under the hood the actual work is effeciently done by the React.js engine.

Reactrb components are isomorphic meaning they can run on the server as well as the client. This means that the initial expansion of the component tree to markup is done server side, just like ERB, or HAML templates. Then the same code runs on the client and will respond to any events.

Reactrb integrates well with Rails, Sinatra, and simple static sites, and can be added to existing web pages very easily, or it can be used to deliver complete websites.

Why ?

  • Single Language: Use Ruby everywhere, no JS, markup languages, or JSX
  • Powerful DSL: Describe HTML and event handlers with a minimum of fuss
  • Ruby Goodness: Use all the features of Ruby to create reusable, maintainable UI code
  • React Simplicity: Nothing is taken away from the React.js model
  • Enhanced Features: Enhanced parameter and state management and other new features
  • Plays well with Others: Works with other frameworks, React.js components, Rails, Sinatra and static web pages

Problems, Questions, Issues

Upgrading to Reactrb

The original gem react.rb was superceeded by reactive-ruby, which has had over 15,000 downloads. This name has now been superceeded by reactrb (see #144 for detailed discussion on why.)

Going forward the name reactrb will be used consistently as the organization name, the gem name, the domain name, the twitter handle, etc.

The first initial version of reactrb is 0.8.x.

It is very unlikely that there will be any more releases of the reactive-ruby gem, so users should upgrade to reactrb.

There are no syntactic or semantic breaking changes between reactrb v 0.8.x and previous versions, however the reactrb gem does not include the react-js source as previous versions did. This allows you to pick the react js source compatible with other gems and react js components you may be using.

Follow these steps to upgrade:

  1. Replace reactive-ruby with reactrb both in Gemfile and any requires in your code.
  2. To include the React.js source, the suggested way is to add require 'react/react-source' before require 'reactrb'. This will use the copy of React.js source from react-rails gem.


Upcoming will be an 0.9.x release which will deprecate a number of features and DSL elements. click for detailed feature list

Version 0.10.x will not be 100% backward compatible with 0.3.0 (react.rb) or 0.7.x (reactive-ruby) so its very important to begin your upgrade process now by switching to reactrb now.

Please let us know either at or via an issue if you have specific concerns with the upgrade from 0.3.0 to 0.10.x.


git clone the project.

To play with some live examples cd to the project directory then

  1. cd example/examples
  2. bundle install
  3. bundle exec rackup
  4. Open http://localhost:9292


  1. cd example/rails-tutorial
  2. bundle install
  3. bundle exec rails s
  4. Open http://localhost:3000


  1. cd example/sinatra-tutorial
  2. bundle install
  3. bundle exec rackup
  4. Open http://localhost:9292

Note that these are very simple examples, for the purpose of showing how to configure the gem in various server environments. For more examples and information see


  1. Run bundle exec rake test_app to generate a dummy test app.
  2. bundle exec rake


This project is still in early stage, so discussion, bug reports and PRs are really welcome :wink:.


In short, Reactrb is available under the MIT license. See the LICENSE file for more info.