title: getting hidden Django field with JavaScript
body: <p>In my form I have a hidden FloatField:</p>
  
  <pre><code>test         = forms.FloatField( widget=forms.HiddenInput())
  </code></pre>
  
  <p>Django generates the following html:</p>
  
  <pre><code>&lt;input type="hidden" name="test_set-0-test" id="id_test_set-0-test" /&gt;
  </code></pre>
  
  <p>I want to silently fill this field with JavaScript:</p>
  
  <pre><code>document.getElementById('id_test_set-0-test').value = X
  </code></pre>
  
  <p>But I do not know if Django will always generate the same id "id_test_set-0-test"?</p>
  
  <p>Is there a better way for finding in JavaScript Django element by id?</p>
  
  <p>Or maybe its possible to enforce id in Django backend?</p>
  
  <p>Thans!</p>