react-rails is a ruby gem which makes it easier to use React and JSX in your Ruby on Rails application.

This is done in 2 ways:

1. making it easy to include react.js as part of your dependencies in application.js.
2. transforming JSX into regular JS on request, or as part of asset precompilation.

We're specifically targeting versions of Ruby on Rails which make use of the asset pipeline, which means Rails 3.1+.

As with all gem dependencies, we strongly recommend adding react-rails to your Gemfile and using bundler to manage your application's dependencies.

# Gemfile

gem 'react-rails', '~> 0.13.0.1'

In order to use React client-side in your application, you must make sure the browser requests it. One way to do that is to drop react.js into app/assets/javascript/ and by default your application manifest will pick it up. There are downsides to this approach, so we made it even easier. Once you have react-rails installed, you can just add a line into your config file (see Configuring) and require react directly in your manifest:

You can require it in your manifest:

// app/assets/application.js

//= require react

Alternatively, you can include it directly as a separate script tag:

# app/views/layouts/application.erb.html

<%= javascript_include_tag "react" %>

To transform your JSX into JS, simply create .js.jsx files. These files will be transformed on request, or precompiled as part of the assets:precompile task.

There are 2 variants available. :development gives you the unminified version of React. This provides extra debugging and error prevention. :production gives you the minified version of React which strips out comments and helpful warnings, and minifies.

# config/environments/development.rb
MyApp::Application.configure do
  config.react.variant = :development
end

# config/environments/production.rb
MyApp::Application.configure do
  config.react.variant = :production
end

Beginning with React v0.5, there is another type of build. This build ships with some "add-ons" that might be useful - take a look at the React documentation for details. In order to make these available, we've added another configuration (which defaults to false).

MyApp::Application.configure do
  config.react.addons = true
end

It is possible to use JSX with CoffeeScript. We need to embed JSX inside backticks so CoffeeScript ignores the syntax it doesn't understand. Here's an example:

Component = React.createClass
  render: ->
    `<ExampleComponent videos={this.props.videos} />`

You can use the --harmony or --strip-types options by adding a configuration to application.rb:

config.react.jsx_transform_options = {
  harmony: true,
  strip_types: true, # for removing Flow type annotations
}