Ruby on Rails - jQuery.countdown no display

Question

Before I move to RoR I was using this great jQuery countdown and it worked fine. I try to use it again in my Rails (4.0.8) application but I can't figure it why nothing is displayed.

I have in app/assets/javascripts (among others) :

application.js
jquery.countdown.min.js
jquery-2.1.1.min.js

In my application.js :

//= require_tree .
//= require jquery-2.1.1.min
//= require jquery.countdown.min

In my Gemfile :

gem 'jquery-rails', '3.0.4'

In my app/views/pages/page.html.erb :

<br />
--
<div data-countdown="2016/01/01"></div>
--

<script type="text/javascript">
  $('[data-countdown]').each(function() {
   var $this = $(this), finalDate = $(this).data('countdown');
   $this.countdown(finalDate, function(event) {
     $this.html(event.strftime('%D days %H:%M:%S'));
   });
 });
</script>

Like documented on this page but nothing shows up.

Am I missing something obvious ? Thanks for your help.

Answer 1

I managed to display my countdown again !

I found (printing the javascript console) that I have the error $ is not defined . So I remove gem 'jquery-rails', '3.0.4' from my Gemfile and perform the command gem uninstall jquery-rails . Then I added those few lines in my header and restarted the server.

<%= javascript_include_tag "jquery-2.1.1.min" %>
<%= javascript_include_tag "jquery.countdown.min" %>