React.rb

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

It lets you write reactive UI components, with Ruby's elegance and compiled to run in JavaScript. ❤️

Installation

# Gemfile
gem "react.rb"

and in your Opal application,

require "opal"
require "react"

React.render(React.create_element('h1'){ "Hello World!" }, `document.body`)

For integration with server (Sinatra, etc), see setup of TodoMVC or the official docs of Opal.

Usage

A Simple Component

A ruby class which define method render is a valid component.

class HelloMessage
  def render
    React.create_element("div") { "Hello World!" }
  end
end

puts React.render_to_static_markup(React.create_element(HelloMessage))

# => '<div>Hello World!</div>'

More complicated one

To hook into native ReactComponent life cycle, the native this will be passed to the class's initializer. And all corresponding life cycle methods (componentDidMount, etc) will be invoked on the instance using the snake-case method name.

class HelloMessage
  def initialize(native)
    @native = Native(native)
  end

  def component_will_mount
    puts "will mount!"
  end

  def render
    React.create_element("div") { "Hello #{@native[:props][:name]}!" }
  end
end

puts React.render_to_static_markup(React.create_element(HelloMessage, name: 'John'))

# => will_mount!
# => '<div>Hello John!</div>'

React::Component

Hey, we are using Ruby, simply include React::Component to save your typing and have some handy methods defined.

class HelloMessage
  include React::Component
  MSG = {great: 'Cool!', bad: 'Cheer up!'}

  define_state(:foo) { "Default greeting" }

  before_mount do
    self.foo = "#{self.foo}: #{MSG[params[:mood]]}"
  end

  after_mount :log

  def log
    puts "mounted!"
  end

  def render
    div do
      span { self.foo + " #{params[:name]}!" }
    end
  end
end

class App
  include React::Component

  def render
    present HelloMessage, name: 'John', mood: 'great'
  end
end

puts React.render_to_static_markup(React.create_element(App))

# => '<div><span>Default greeting: Cool! John!</span></div>'

React.render(React.create_element(App), `document.body`)

# mounted!

• Callback of life cycle could be created through helpers before_mount, after_mount, etc
• this.props is accessed through method self.params
• Use helper method define_state to create setter & getter of this.state for you
• For the detailed mapping to the original API, see this issue for reference. Complete reference will come soon.

Element Building DSL

As a replacement of JSX, include React::Component and you can build React.Element hierarchy without all the React.create_element noises.

def render
  div do
    h1 { "Title" }
    h2 { "subtitle"}
    div(class_name: 'fancy', id: 'foo') { span { "some text #{interpolation}"} }
    present FancyElement, fancy_props: '10'
  end
end

Props validation

How about props validation? Inspired by Grape API, props validation rule could be created easily through params class method as below,

class App
  include React::Component

  params do
    requires :username, type: String
    requires :enum, values: ['foo', 'bar', 'awesome']
    requires :payload, type: Todo # yeah, a plain Ruby class
    optional :filters, type: Array[String]
    optional :flash_message, type: String, default: 'Welcome!' # no need to feed through `getDefaultProps`
  end

  def render
    div
  end
end

Mixins

Simply create a Ruby module to encapsulate the behavior. Example below is modified from the original React.js Exmaple on Mixin. Opal Browser syntax are used here to make it cleaner.

module SetInterval
  def self.included(base)
    base.class_eval do
      before_mount { @interval = [] }
      before_unmount do
        # abort associated timer of a component right before unmount
        @interval.each { |i| i.abort }
      end
    end
  end

  def set_interval(seconds, &block)
    @interval << $window.every(seconds, &block)
  end
end

class TickTock
  include React::Component
  include SetInterval

  define_state(:seconds) { 0 }

  before_mount do
    set_interval(1) { self.seconds = self.seconds + 1 }
    set_interval(1) { puts "Tick!" }
  end

  def render
    span do
      "React has been running for: #{self.seconds}"
    end
  end
end

React.render(React.create_element(TickTock), $document.body.to_n)

$window.after(5) do
  React.unmount_component_at_node($document.body.to_n)
end

# => Tick!
# => ... for 5 times then stop ticking after 5 seconds

Example

• React Tutorial: see example/react-tutorial, the original CommentBox example.
• TodoMVC: see example/todos, your beloved TodoMVC <3.

TODOS

• Documentation
• API wrapping coverage of the original js library (pretty close though)
• React Native?

Developing

To run the test case of the project yourself.

1. git clone the project
2. bundle install
3. bundle exec rackup
4. Open http://localhost:9292 to run the spec

Contributions

This project is still in early stage, so discussion, bug report and PR are really welcome 😉.

Contact

David Chang @zetachang

License

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