module YourApp
  class Application < Rails::Application

    # ...

    config.middleware.insert_before 0, "Rack::Cors" do
      allow do
        origins '*' # or any domain
        # origins 'localhost:3000'
        resource '*', :headers => :any, :methods => [:get, :post, :options]
        # resource '/public/*', :headers => 'x-domain-token', :methods => :get
      end
    end

  end
end