title: jQuery: checking if the value of a field is null (empty)
body: <p>Is this a good way to check if the value of a field is <code>null</code>?</p>
  
  <pre><code>if($('#person_data[document_type]').value() != 'NULL'){}
  </code></pre>
  
  <p>Or is there a better way?</p>