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For a complete example of this gem, see our live demo at (Source Code)

Aloha from Justin Gordon (bio) and the ShakaCode Team! We're actively looking for new projects involving React, React-Native, and Rails, including conversion of AngularJs to React. Please contact me if we could potentially help you in any way. Besides consulting on bigger projects, ShakaCode is doing ScreenHero plus Slack/Github based coaching for React on Rails. See our blog post Can ShakaCode Help You? for more information.

I'm offering a free half-hour project consultation, on anything from React on Rails to any aspect of web application development for both consumer and enterprise products. In addition to React.js and Rails, we're doing React-Native iOS and Android apps!

Whether you have a new project or need help on an existing project, feel free to contact me directly at and thanks in advance for any referrals!

Your support keeps this project going!

(Want to become a contributor? Contact us for a Slack room invite and let us know that you want to contribute.)


Please Subscribe to keep in touch with Justin Gordon and ShakaCode. I intend to send a monthly summary including announcements of new releases of React on Rails and of our latest blog articles and tutorials. Subscribers will also have access to exclusive content, including tips and examples.



From Joel Hooks, Co-Founder, Chief Nerd at, January 30, 2017: 2017-01-30_11-33-59

For more testimonials, see Live Projects and Kudos.

Articles, Videos, and Podcasts



  1. Creating a component with React on Rails
  2. Creating a redux component with React on Rails
  3. React On Rails Tutorial Series
    1. History and Motivation
    2. Basic Tutorial Walkthrough
    3. Code Walkthrough



React on Rails

Project Objective: To provide an opinionated and optimal framework for integrating Ruby on Rails with modern JavaScript tooling and libraries, including Webpack, Babel, React, Redux, React-Router. This differs significantly from typical Rails architecture. When considering what goes into react_on_rails, we ask ourselves, is the functionality related to the intersection of using Rails and modern JavaScript? If so, then the functionality belongs right here. In other cases, we're releasing separate npm packages or Ruby gems. If you are interested in implementing React using traditional Rails architecture, see react-rails.

React on Rails integrates Facebook's React front-end framework with Rails. React v0.14.x and greater is supported, with server rendering. Redux and React-Router are supported as well, also with server rendering, using either execJS or a Node.js server. See the Rails on Maui blog post that started it all!

Table of Contents


Like the react-rails gem, React on Rails is capable of server-side rendering with fragment caching and is compatible with turbolinks. Unlike react-rails, which depends heavily on sprockets and jquery-ujs, React on Rails uses webpack and does not depend on jQuery. While the initial setup is slightly more involved, it allows for advanced functionality such as:

See the react-webpack-rails-tutorial for an example of a live implementation and code.

Why Webpack?

Webpack is used to generate several JavaScript "bundles" for inclusion in application.js or directly in your layout.

This usage of webpack fits neatly and simply into the existing Rails sprockets system and you can include React components on a Rails view with a simple helper.

Compare this to some alternative approaches for SPAs (Single Page Apps) that utilize Webpack and Rails. They will use a separate node server to distribute web pages, JavaScript assets, CSS, etc., and will still use Rails as an API server. A good example of this is our ShakaCode team member Alex's article Universal React with Rails: Part I.

We're definitely not doing that. With react_on_rails, webpack is mainly generating a nice JavaScript file for inclusion into application.js. We're going to KISS. And that's all relative given how much there is to get right in an enterprise class web application.

Getting Started

For more detailed instructions, see the React on Rails Basic Tutorial.

  1. Add the following to your Gemfile and bundle install.

    gem "react_on_rails", "~> 6"
  2. Commit this to git (you cannot run the generator unless you do this or pass the option --ignore-warnings).

  3. See help for the generator:

    rails generate react_on_rails:install --help
  4. Run the generator with a simple "Hello World" example (more options below):

    rails generate react_on_rails:install
  5. Bundle and NPM install. Make sure you are on a recent version of node. Please use at least Node v5. Bundle is for adding execJs. You can remove that if you are sure you will not server render.

    bundle && yarn
  6. Ensure that you have foreman installed: gem install foreman.

  7. Start your Rails server:

    foreman start -f
  8. Visit localhost:5000/hello_world. Note, foreman defaults to PORT 5000 unless you set the value of PORT in your environment. For example, you can export PORT=3000 to use the Rails default port of 3000.

Installation Summary

See the Installation Overview for a concise set summary of what's in a React on Rails installation.

Initializer Configuration

Configure the config/initializers/react_on_rails.rb. You can adjust some necessary settings and defaults. See file spec/dummy/config/initializers/react_on_rails.rb for a detailed example of configuration, including comments on the different values to configure.

Including your React Component in your Rails Views

  • Normal Mode (React component will be rendered on client):

    <%= react_component("HelloWorldApp", props: @some_props) %>
  • Server-Side Rendering (React component is first rendered into HTML on the server):

    <%= react_component("HelloWorldApp", props: @some_props, prerender: true) %>
  • The component_name parameter is a string matching the name you used to expose your React component globally. So, in the above examples, if you had a React component named "HelloWorldApp," you would register it with the following lines:

    import ReactOnRails from 'react-on-rails';
    import HelloWorldApp from './HelloWorldApp';
    ReactOnRails.register({ HelloWorldApp });

    Exposing your component in this way is how React on Rails is able to reference your component from a Rails view. You can expose as many components as you like, as long as their names do not collide. See below for the details of how you expose your components via the react_on_rails webpack configuration.

  • @some_props can be either a hash or JSON string. This is an optional argument assuming you do not need to pass any options (if you want to pass options, such as prerender: true, but you do not want to pass any properties, simply pass an empty hash {}). This will make the data available in your component:

      # Rails View
      <%= react_component("HelloWorldApp", props: { name: "Stranger" }) %>
      // inside your React component // "Stranger"


You can enable the i18n functionality with react-intl.

React on Rails provides an option for automatic conversions of Rails *.yml locale files into *.js files for react-intl.

See the How to add I18n for a summary of adding I18n.


All JavaScript in React On Rails is loaded from npm: react-on-rails. To manually install this (you did not use the generator), assuming you have a standard configuration, run this command:

cd client && yarn add react-on-rails

That will install the latest version and update your package.json.

How it Works

The generator installs your webpack files in the client folder. Foreman uses webpack to compile your code and output the bundled results to app/assets/webpack, which are then loaded by sprockets. These generated bundle files have been added to your .gitignore for your convenience.

Inside your Rails views, you can now use the react_component helper method provided by React on Rails. You can pass props directly to the react component helper. You can also initialize a Redux store with view or controller helper redux_store so that the store can be shared amongst multiple React components. See the docs for redux_store below and scan the code inside of the /spec/dummy sample app.

Client-Side Rendering vs. Server-Side Rendering

In most cases, you should use the prerender: false (default behavior) with the provided helper method to render the React component from your Rails views. In some cases, such as when SEO is vital, or many users will not have JavaScript enabled, you can enable server-rendering by passing prerender: true to your helper, or you can simply change the default in config/initializers/react_on_rails.

Now the server will interpret your JavaScript using ExecJS and pass the resulting HTML to the client. We recommend using mini_racer as ExecJS's runtime. The generator will automatically add it to your Gemfile for you (once we complete #501).

In the following screenshot you can see the 3 parts of React on Rails rendering:

  1. A hidden HTML div that contains the properties of the React component, such as the registered name and any props. A JavaScript function runs after the page loads to convert take this data and build initialize React components.
  2. The wrapper div <div id="HelloWorld-react-component-0"> specifies the div where to place the React rendering. It encloses the server-rendered HTML for the React component
  3. Additional JavaScript is placed to console log any messages, such as server rendering errors. Note, these server side logs can be configured to only be sent to the server logs.

Note: If server rendering is not used (prerender: false), then the major difference is that the HTML rendered for the React component only contains the outer div: <div id="HelloWorld-react-component-0"/>. The first specification of the React component is just the same.

Comparison of a normal React Component with its server-rendered version

Building the Bundles

Each time you change your client code, you will need to re-generate the bundles (the webpack-created JavaScript files included in application.js). The included Foreman will take care of this for you by watching your JavaScript code files for changes. Simply run foreman start -f

On production deployments that use asset precompilation, such as Heroku deployments, React on Rails, by default, will automatically run webpack to build your JavaScript bundles. You can see the source code for what gets added to your precompilation here. For more information on this topic, see the doc on Heroku deployment.

If you have used the provided generator, these bundles will automatically be added to your .gitignore to prevent extraneous noise from re-generated code in your pull requests. You will want to do this manually if you do not use the provided generator.

Rails Context

When you use a "generator function" to create react components (or renderedHtml on the server) or you used shared redux stores, you get 2 params passed to your function:

  1. Props that you pass in the view helper of either react_component or redux_store
  2. Rails contextual information, such as the current pathname. You can customize this in your config file.

This information (props and railsContext) should be the same regardless of either client or server side rendering.

While you could manually pass the railsContext information in as "props", the rails_context is a convenience because it's passed consistently to all invocations of generator functions.

So if you register your generator function MyAppComponent, it will get called like:

reactComponent = MyAppComponent(props, railsContext);

and for a store:

reduxStore = MyReduxStore(props, railsContext);

Note, you never make these calls. This is what React on Rails does when either server or client rendering. You'll be defining functions that take these params and return a React component or a Redux Store.

(Note, see below section on how to setup redux stores that allow multiple components to talk to the same store.)

The railsContext has: (see implementation in file react_on_rails_helper.rb, method rails_context for the definitive list).

    # URL settings
    href: request.original_url,
    location: "#{uri.path}#{uri.query.present? ? "?#{uri.query}": ""}",
    scheme: uri.scheme, # http
    host:, #
    port: uri.port,
    pathname: uri.path, # /posts
    search: uri.query, # id=30&limit=5

    # Other
    serverSide: boolean # Are we being called on the server or client? NOTE, if you conditionally
     # render something different on the server than the client, then React will only show the
     # server version!

Use Cases

Needing the current url path for server rendering

Suppose you want to display a nav bar with the current navigation link highlighted by the URL. When you server render the code, you will need to know the current URL/path if that is what you want your logic to be based on. The new railsContext has this information so the application of an "active" class can be done server side.

Configuring different code for server side rendering

Suppose you want to turn off animation when doing server side rendering. The serverSide value is just what you need.

Customization of the rails_context

You can customize the values passed in the railsContext in your config/initializers/react_on_rails.rb. Here's how.

Set the config value for the rendering_extension:

  config.rendering_extension = RenderingExtension

Implement it like this above in the same file. Create a class method on the module called custom_context that takes the view_context for a param.

See spec/dummy/config/initializers/react_on_rails.rb for a detailed example.

module RenderingExtension

  # Return a Hash that contains custom values from the view context that will get merged with
  # the standard rails_context values and passed to all calls to generator functions used by the
  # react_component and redux_store view helpers
  def self.custom_context(view_context)
     somethingUseful: view_context.session[:something_useful]

In this case, a prop and value for somethingUseful will go into the railsContext passed to all react_component and redux_store calls. You may set any values available in the view rendering context.

Globally Exposing Your React Components

Place your JavaScript code inside of the provided client/app folder. Use modules just as you would when using webpack alone. The difference here is that instead of mounting React components directly to an element using React.render, you expose your components globally and then mount them with helpers inside of your Rails views.

This is an example of how to expose a component to the react_component view helper.

  // client/app/bundles/HelloWorld/startup/HelloWorldApp.jsx
  import HelloWorld from '../components/HelloWorld';
  import ReactOnRails from 'react-on-rails';
  ReactOnRails.register({ HelloWorld });

Different Server-Side Rendering Code (and a Server Specific Bundle)

You may want different initialization for your server rendered components. For example, if you have animation that runs when a component is displayed, you might need to turn that off when server rendering. However, the railsContext will tell you if your JavaScript code is running client side or server side. So code that required a different server bundle previously may no longer require this!

If you do want different code to run, you'd setup a separate webpack compilation file and you'd specify a different, server side entry file. ex. 'serverHelloWorldApp.jsx'. Note, you might be initializing HelloWorld with version specialized for server rendering.

Generator Functions

Why would you create a function that returns a React component? For example, you may want the ability to use the passed-in props to initialize a redux store or setup react-router. Or you may want to return different components depending on what's in the props. ReactOnRails will automatically detect a registered generator function.

Another reason to user a generator function is that sometimes in server rendering, specifically with React Router, you need to return the result of calling ReactDOMServer.renderToString(element). You can do this by returning an object with the following shape: { renderedHtml, redirectLocation, error }.

Renderer Functions

A renderer function is a generator function that accepts three arguments: (props, railsContext, domNodeId) => { ... }. Instead of returning a React component, a renderer is responsible for calling ReactDOM.render to manually render a React component into the dom. Why would you want to call ReactDOM.render yourself? One possible use case is code splitting.

Renderer functions are not meant to be used on the server, since there's no DOM on the server. Instead, use a generator function. Attempting to server render with a renderer function will cause an error.

ReactOnRails View Helpers API

Once the bundled files have been generated in your app/assets/webpack folder and you have exposed your components globally, you will want to run your code in your Rails views using the included helper method.

This is how you actually render the React components you exposed to window inside of clientRegistration (and global inside of serverRegistration if you are server rendering).


                props: {},
                prerender: nil,
                trace: nil,
                replay_console: nil,
                raise_on_prerender_error: nil,
                id: nil,
                html_options: {})
  • component_name: Can be a React component, created using a ES6 class, or React.createClass, a generator function that returns a React component (or only on the server side, an object with shape { redirectLocation, error, renderedHtml }), or a renderer function that manually renders a React component to the dom (client side only).
  • options:
    • props: Ruby Hash which contains the properties to pass to the react object, or a JSON string. If you pass a string, we'll escape it for you.
    • prerender: enable server-side rendering of component. Set to false when debugging!
    • id: Id for the div, will be used to attach the React component. This will get assigned automatically if you do not provide an id. Must be unique.
    • html_options: Any other html options to get placed on the added div for the component. For example, you can set a class (or inline style) on the outer div so that it behaves like a span, with styling of display:inline-block.
    • trace: set to true to print additional debugging information in the browser. Defaults to true for development, off otherwise. Note, on the client you will so both the railsContext and your props. On the server, you only see the railsContext being logged.
    • replay_console: Default is true. False will disable echoing server-rendering logs to the browser. While this can make troubleshooting server rendering difficult, so long as you have the default configuration of logging_on_server set to true, you'll still see the errors on the server.
    • raise_on_prerender_error: Default is false. True will throw an error on the server side rendering. Your controller will have to handle the error.


Controller Extension

Include the module ReactOnRails::Controller in your controller, probably in ApplicationController. This will provide the following controller method, which you can call in your controller actions:

redux_store(store_name, props: {})

  • store_name: A name for the store. You'll refer to this name in 2 places in your JavaScript:
    1. You'll call ReactOnRails.registerStore({storeName}) in the same place that you register your components.
    2. In your component definition, you'll call ReactOnRails.getStore('storeName') to get the hydrated Redux store to attach to your components.
  • props: Named parameter props. ReactOnRails takes care of setting up the hydration of your store with props from the view.

For an example, see spec/dummy/app/controllers/pages_controller.rb. Note, this is preferable to using the equivalent view_helper redux_store in that you can be assured that the store is initialized before your components.

View Helper

redux_store(store_name, props: {})

Same API as the controller extension. HOWEVER, we recommend the controller extension instead because the Rails executes the template code in the controller action's view file (erb, haml, slim, etc.) before the layout. So long as you call redux_store at the beginning of your action's view file, this will work. However, it's an easy mistake to put this call in the wrong place. Calling redux_store in the controller action ensures proper load order, regardless of where you call this in the controller action. Note, you won't know of this subtle ordering issue until you server render and you find that your store is not hydrated properly.


Place this view helper (no parameters) at the end of your shared layout. This tell ReactOnRails where to client render the redux store hydration data. Since we're going to be setting up the stores in the controllers, we need to know where on the view to put the client side rendering of this hydration data, which is a hidden div with a matching class that contains a data props. For an example, see spec/dummy/app/views/layouts/application.html.erb.

Redux Store Notes

Note, you don't need to separately initialize your redux store. However, it's recommended for the two following use cases:

  1. You want to have multiple components that access the same store.
  2. You want to place the props to hydrate the client side stores at the very end of your HTML so that the browser can render all earlier HTML first. This is particularly useful if your props will be large.


server_render_js(js_expression, options = {})

  • js_expression, like 2 + 3, and not a block of js code. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught and console messages handled properly
  • Currently, the only option you may pass is replay_console (boolean)

This is a helper method that takes any JavaScript expression and returns the output from evaluating it. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught and console messages handled properly.

Multiple React Components on a Page with One Store

You may wish to have 2 React components share the same the Redux store. For example, if your navbar is a React component, you may want it to use the same store as your component in the main area of the page. You may even want multiple React components in the main area, which allows for greater modularity. In addition, you may want this to work with Turbolinks to minimize reloading the JavaScript. A good example of this would be something like a notifications counter in a header. As each notification is read in the body of the page, you would like to update the header. If both the header and body share the same Redux store, then this is trivial. Otherwise, we have to rely on other solutions, such as the header polling the server to see how many unread notifications exist.

Suppose the Redux store is called appStore, and you have 3 React components that each needs to connect to a store: NavbarApp, CommentsApp, and BlogsApp. I named them with App to indicate that they are the registered components.

You will need to make a function that can create the store you will be using for all components and register it via the registerStore method. Note, this is a storeCreator, meaning that it is a function that takes (props, location) and returns a store:

function appStore(props, railsContext) {
  // Create a hydrated redux store, using props and the railsContext (object with
  // Rails contextual information).
  return myAppStore;


When registering your component with React on Rails, you can get the store via ReactOnRails.getStore:

// getStore will initialize the store if not already initialized, so creates or retrieves store
const appStore = ReactOnRails.getStore("appStore");
return (
  <Provider store={appStore}>
    <CommentsApp />

From your Rails view, you can use the provided helper redux_store(store_name, props) to create a fresh version of the store (because it may already exist if you came from visiting a previous page). Note, for this example, since we're initializing this from the main layout, we're using a generic name of @react_props. This means in this case that Rails controllers would set @react_props to the properties to hydrate the Redux store.


<%= redux_store("appStore", props: @react_props) %>;
<%= react_component("NavbarApp") %>

Components are created as stateless function(al) components. Since you can pass in initial props via the helper redux_store, you do not need to pass any props directly to the component. Instead, the component hydrates by connecting to the store.


<%= react_component("CommentsApp") %>


<%= react_component("BlogsApp") %>

Note: You will not be doing any partial updates to the Redux store when loading a new page. When the page content loads, React on Rails will rehydrate a new version of the store with whatever props are placed on the page.

ReactOnRails JavaScript API

See ReactOnRails JavaScript API.

Using Rails built-in CSRF protection in JavaScript

Rails has built-in protection for Cross-Site Request Forgery (CSRF), see Rails Documentation. To nicely utilize this feature in JavaScript requests, React on Rails is offerring two helpers that can be used as following for POST, PUT or DELETE requests:

import ReactOnRails from 'react-on-rails';

// reads from DOM csrf token generated by Rails in <%= csrf_meta_tags %>
csrfToken = ReactOnRails.authenticityToken();

// compose Rails specific request header as following { X-CSRF-Token: csrfToken, X-Requested-With: XMLHttpRequest }
header = ReactOnRails.authenticityHeaders(otherHeader);

If you are using jquery-ujs for AJAX calls, then these helpers are not needed because the jquery-ujs library updates header automatically, see jquery-ujs documentation.

React Router

React Router is supported, including server side rendering! See:

  1. React on Rails docs for react-router
  2. Examples in spec/dummy/app/views/react_router and follow to the JavaScript code in the spec/dummy/client/app/startup/ServerRouterApp.jsx.
  3. Code Splitting docs for information about how to set up code splitting for server rendered routes.


  • Version 6.0 puts the necessary precompile steps automatically in the rake precompile step. You can, however, disable this by setting certain values to nil in the config/initializers/react_on_rails.rb.
    • config.symlink_non_digested_assets_regex: Set to nil to turn off the setup of non-js assets.
    • npm_build_production_command: Set to nil to turn off the precompilation of the js assets.
  • See the Heroku Deployment doc for specifics regarding Heroku. The information here should apply to other deployments.
  • If you're using the node server for server rendering, you may want to do your own AWS install. We'll have more docs on this in the future. Get in touch if you're keenly interested in this feature.

Integration with Node

Node.js can be used as the backend for server-side rendering instead of execJS. Before you try this, consider the tradeoff of extra complexity with your deployments versus potential performance gains. We've found that using ExecJS with mini_racer to be "fast enough" so far. That being said, we've heard of other large websites using Node.js for better server rendering performance. See Node.js for Server Rendering for more information.

Additional Documentation

Try out our new Documentation Gitbook for improved readability & reference!



  • Ruby 2.1 or greater
  • Rails 3.2 or greater
  • Node 5.5 or greater


Bug reports and pull requests are welcome. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to our version of the Contributor Covenant Code of Conduct).

See Contributing to get started.


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


The Shaka Code team!

The origins of the project began with the need to do a rich JavaScript interface for ShakaCode's client Madrone and the choice to use Webpack and Rails, as described in Fast Rich Client Rails Development With Webpack and the ES6 Transpiler.

The gem project started with Justin Gordon pairing with Samnang Chhun to figure out how to do server rendering with Webpack plus Rails. Alex Fedoseev then joined in. Rob Wise, Aaron Van Bokhoven, and Andy Wang did the bulk of the generators. Many others have contributed.

We owe much gratitude to the work of the react-rails gem.


The following companies support open source, and ShakaCode uses their products!


  • See Projects using and KUDOS for React on Rails. Please submit yours! Please edit either page or email us and we'll add your info. We also love stars as it helps us attract new users and contributors.
  • Follow @railsonmaui and @shakacode on Twitter for updates on releases. We've also got a forum category dedicated to react_on_rails.
  • Please Subscribe to keep in touch with Justin Gordon and ShakaCode. I intend to send a monthly summary including announcements of new releases of React on Rails and of our latest blog articles and tutorials. Subscribers will also have access to exclusive content, including tips and examples.


Aloha from Justin Gordon (bio) and the ShakaCode Team! We're actively looking for new projects involving React, React-Native, and Rails. Please contact me at if we could potentially help you in any way. Besides consulting on bigger projects, ShakaCode is doing Skype plus Slack/Github based coaching for React on Rails. See our blog post Can ShakaCode Help You? for more information.

We're offering a free half-hour project consultation, on anything from React on Rails to any aspect of web application development for both consumer and enterprise products. In addition to React.js and Rails, we're doing React-Native iOS and Android apps!

Whether you have a new project or need help on an existing project, feel free to contact me directly at and thanks in advance for any referrals!

Your support keeps this project going.

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