title: How to integrate jQuery select2 library into a Symfony3 form?
body: <p>I am trying to manually integrate the jQuery <a href="https://select2.github.io/" rel="nofollow"><code>select2</code></a> library into my Symfony form as a replacement for my select boxes.</p>
  
  <p>Following the manual I have added to the page header:</p>
  
  <pre><code>&lt;link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.2-rc.1/css/select2.min.css" rel="stylesheet" /&gt;
  &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.2-rc.1/js/select2.min.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>In addition I have modified my form class, adding <code>attr</code> to each select:</p>
  
  <pre><code>-&gt;add('kontoWinien', EntityType::class, array(
      'class' =&gt; 'AppBundle\Entity\konto',
      'attr' =&gt; array('class'=&gt;'select2')
  ))
  </code></pre>
  
  <p>My modified Twig template:</p>
  
  <pre><code>{{ form_start(form) }}
  &lt;SCRIPT type="text/javascript"&gt;
       $(document).ready(function() {
          $(".select2").select2();
      });
  &lt;/SCRIPT&gt;
  {{ form_widget(form) }}
  {{ form_end(form) }}
  </code></pre>
  
  <p>However <strong>the select2 is still not loaded</strong>. </p>
  
  <p>HTML code generated by symfony3 looks like this:</p>
  
  <pre><code> &lt;head&gt;
      &lt;link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.2-rc.1/css/select2.min.css" rel="stylesheet" /&gt;
      &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.2-rc.1/js/select2.min.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  
  &lt;form name="dziennik" method="post"&gt;
  &lt;script type="text/javascript"&gt;
      $(document).ready(function() {
          $(".select2").select2();
      });
  &lt;/script&gt;
  
  &lt;select id="dziennik_kontoWinien" name="dziennik[kontoWinien]" class="select2 form-control"&gt;
  </code></pre>
  
  <p>Could you please advise what am i doing wrong?</p>