react-rails

react-rails version discaimer This README is for 1.x branch which is still in development. Please switch to latest 0.x branch for stable version.

Additionaly: 0.x branch directly follows React versions, 1.x will not do so.

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

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.
3. View helpers to render React components in an unobtrusive style and/or on the server.

Installation

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
# If you missed a warning at the top of this README - this is still in development
# which means this version is not pushed to rubygems.org

gem 'react-rails', '~> 1.0.0.pre', github: 'reactjs/react-rails'

Usage

react.js

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 vendor/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" %>

JSX

To transform your JSX into JS, simply create .js.jsx files, and ensure that the file has the /** @jsx React.DOM */ docblock. These files will be transformed on request, or precompiled as part of the assets:precompile task.

CoffeeScript files can also be used, by creating .js.jsx.coffee files. You must use this form of the docblock at the top of each file: ###* @jsx React.DOM ###. We also need to embed JSX inside backticks so CoffeeScript ignores the syntax it doesn't understand. Here's an example:

###* @jsx React.DOM ###

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

Unobtrusive JavaScript

react_ujs will call React.renderComponent for every element with data-react-class attribute. React properties can be specified by data-react-props attribute in JSON format. For example:

<!-- react_ujs will execute `React.renderComponent(HelloMessage({name:"Bob"}), element)` -->
<div data-react-class="HelloMessage" data-react-props="<%= {name: 'Bob'}.to_json %>" />

react_ujs will also scan DOM elements and call React.unmountComponentAtNode on page unload. If you want to disable this behavior, remove data-react-class attribute in componentDidMount.

To use react_ujs, simply require it after react (and after turbolinks if Turbolinks is used):

// app/assets/application.js

//= require turbolinks
//= require react
//= require react_ujs

View helper

There is a view helper method react_component. It is designed to work with react_ujs and takes a React class name, properties, and HTML options as arguments:

react_component('HelloMessage', name: 'John')
# <div data-react-class="HelloMessage" data-react-props="{&quot;name&quot;:&quot;John&quot;}"></div>

By default, a <div> element is used. Other tag and HTML attributes can be specified:

react_component('HelloMessage', {name: 'John'}, :span)
# <span data-...></span>

react_component('HelloMessage', {name: 'John'}, {id: 'hello', class: 'foo', tag: :span})
# <span class="foo" id="hello" data-...></span>

Server Rendering

React components can also use the same ExecJS mechanisims in Sprockets to execute JavaScript code on the server, and render React components to HTML to be delivered to the browser, and then the react_ujs script will cause the component to be mounted. In this way, users get fast initial page loads and search-engine-friendly pages.

ExecJS

By default, ExecJS will use node.js in an external process to run JS code. Because we will be executing JS on the server in production, an in-process, high-performance JS VM should be used. Simply add the proper one for your platform to your Gemfile:

gem "therubyracer", :platforms => :ruby
gem "therubyrhino", :platforms => :jruby

components.js

In order for us to render your React components, we need to be able to find them and load them into the JS VM. By convention, we look for a assets/components.js file through the asset pipeline, and load that. For example:

// app/assets/javascripts/components.js
//= require_tree ./components

This will bring in all files located in the app/assets/javascripts/components directory. You can organize your code however you like, as long as a request for /assets/components.js brings in a concatenated file containing all of your React components, and each one has to be available in the global scope (either window or global can be used). For .js.jsx files this is not a problem, but if you are using .js.jsx.coffee files then the wrapper function needs to be taken into account:

###* @jsx React.DOM ###

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

window.Component = Component

View Helper

To take advantage of server rendering, use the same view helper react_component, and pass in prerender: true in the options hash.

react_component('HelloMessage', {name: 'John'}, {prerender: true})

This will return the fully rendered component markup, and as long as you have included the react_ujs script in your page, then the component will also be instantiated and mounted on the client.

Configuring

Variants

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

Add-ons

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

Server Rendering

For performance and thread-safety reasons, a pool of JS VMs are spun up on application start, and the size of the pool and the timeout on requesting a VM from the pool are configurable. You can also say where you want to grab the react.js code from, and if you want to change the filenames for the components (this should be an array of filenames that will be requested from the asset pipeline and concatenated together.)

# config/environments/application.rb
# These are the defaults if you dont specify any yourself
MyApp::Application.configure do
  config.react.max_renderers = 10
  config.react.timeout = 20 #seconds
  config.react.react_js = lambda {File.read(::Rails.application.assets.resolve('react.js'))}
  config.react.component_filenames = ['components.js']
end

CoffeeScript

It is possible to use JSX with CoffeeScript. The caveat is that you will still need to include the docblock. Since CoffeeScript doesn't allow /* */ style comments, we need to do something a little different. We also need to embed JSX inside backticks so CoffeeScript ignores the syntax it doesn't understand. Here's an example:

###* @jsx React.DOM ###

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

Changing react.js and JSXTransformer.js versions

In some cases you may want to have your react.js and JSXTransformer.js files come from a different release than the one, that is specified in the react-rails.gemspec. To achieve that, you have to manually replace them in your app.

Instructions

Just put another version of react.js or JSXTransformer.js under /vendor/assets/react directory. If you need different versions of react.js for production and development, then use a subdirectory named after config.react.variant, e.g. you set config.react.variant = :development so for this environment react.js is expected to be in /vendor/assets/react/development

Things to remember

If you replace JSXTransformer.js in production environment, you have to restart your rails instance, because the jsx compiler context is cached.

Name of the JSXTransformer.js file is case-sensitive.