title: How can the file extension be validated in an input type file using JQuery?
body: <p>HTML:</p>
  
  <pre><code>&lt;input type="file" name="group_documents_file" id="group_documents_file" class="group-documents-file" /&gt;
  </code></pre>
  
  <p>Rule: The file to upload must have an extension JPEG, GIF or PNG, otherwise an alert must be displayed.</p>