gistfile1.txt

 11 // element is expected to be a form element and contain a submit and file field
 12 function update_form_with_progress_bar(element) {
 13   // disable submit button
 14   submit_button = element.down("input[type='submit']");
 15   submit_button.disable();
 16 
 17   // if file field has a value, display progress bar
 18   file_field = element.down("input[type='file']");
 19   if ( file_field != '' && file_field != null ) {
 20     submit_button.hide();      
 21 
 22     // display or insert progress bar stuff here
 23   }             
 24 }



  <div id="pandaloader">
    <div id="uploader">
      <form id="upload" enctype="multipart/form-data" action="index.html" method="post">
        <%= file_upload_field('', 'file') %>
        <input type="submit" value="Upload">
      </form>
    </div>

      <div id="progress" class="bar" style="width: 300px; background:#EEEEE none repeat scroll 0 0&nbsp; border: 1px solid #222222; margin-top:20px">
        <div id="progressbar" style="background:#333333 none repeat scroll 0 0; height:24px; width:0px;">test&nbsp;</div>
      </div>
  </div>