不要从gem'jquery-ui-rails'工作datepicker

Question

Version Rails 5 beta 3.我使用的是gem jquery-ui-rails 5.0.5

的Gemfile

................................................
      gem 'jquery-rails'      
      # Use SCSS for stylesheets
      gem 'sass-rails', '~> 5.0'
      # Use Uglifier as compressor for JavaScript assets
      gem 'uglifier', '>= 1.3.0'
      # Use CoffeeScript for .coffee assets and views
      gem 'coffee-rails', '~> 4.1.0'
      gem 'jquery-ui-rails'

的application.js：

//= require turbolinks
//= require jquery
//= require jquery-ui/datepicker
//= require jquery_ujs
//= require jquery.turbolinks
//= require cocoon
//= require jquery_nested_form
//= require jquery-fileupload/basic

application.css

/**
 * application.css
 *
 *= require jquery-ui/datepicker
 *= require_self
 *= require_tree ./all

自由职业者/ edit.html.erb

<li class="form-fields__group form-fields__group_birthdate">
        <label for="freelancer_birth_date">Birthday</label>
        <div class= "field">
          <%= f.text_field :birthday %>
        </div>
      </li>

表名：自由职业者

#
#  id             :integer          not null, primary key
#  first_name     :string
#  last_name      :string
#  rate           :integer
#  birthday       :date

Javascript角/ freelancer.coffee

jQuery ->
  $('#freelancer_birthday').datepicker() 

我点击字段生日，但不要打开datepicker。什么都没发生。怎么能解决这个问题？谢谢