opal-konckout is wraper of knockout.js.

Installation

Add this line to your application's Gemfile:

gem 'opal-knockout'

And then execute:

$ bundle

Or install it yourself as:

$ gem install opal-knockout

Usage(Rails)

Gemfile

source 'https://rubygems.org'
gem 'opal-knockout'
source 'https://rails-assets.org' do
  gem 'rails-assets-knockoutjs', '3.3.0'
end

Opal

app/assets/javascripts/user_view_model.rb

class User
  attr_accessor :first_name, :last_name
  def initialize(first_name, last_name)
    self.first_name = first_name
    self.last_name = last_name
  end
end
class UserViewModel < Knockout::ViewModel
  attr_observable :first_name, :last_name
  attr_observable_array :users
  attr_computed :full_name, :show_full_name
  def initialize(first_name, last_name)
    self.first_name = first_name
    self.last_name = last_name
  end
  def add_users
    self.users.push(User.new(
                      self.first_name.to_s,
                      self.last_name.to_s
                    )
    )
    clear_form
  end
  private
  def show_full_name
    "#{first_name.to_s} #{last_name.to_s}"
  end
  def clear_form
    self.first_name = ''
    self.last_name = ''
  end
end

app/assets/javascripts/application.rb

#= require opal
#= require knockoutjs
#= require opal-knockout
#= require_tree .
#= require_self
$root_view_model = Knockout::RootViewModel.new(
    user: UserViewModel.new('Taro', 'Yamada')
)
Knockout.apply_bindings($root_view_model)

View

app/views/users/index.html.slim

div data-bind="with: user"
  form
    label
      | First Name
    input type="text" data-bind="textInput: first_name"
    br
    label
      | Last Name
    input type="text" data-bind="textInput: last_name"
    p data-bind="text: full_name"
    button type="button" data-bind="click: $add_users"
  ul data-bind="foreach: users"
    li
      span data-bind="text: first_name"
      | &nbsp;
      span data-bind="text: last_name"

Contributing

Fork it ( https://github.com/patorash/opal-knockout/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request