[Zope] how to fill form values name:int in javascript?

Hi, This is typically not zope question, but I does not find solution for this zopiness. I need to fill from javascript form fields with defined zope type: <input type="text" name="number:int" value="0"> and how to address it in javascript? This make JS error for me: document.forms['form_name'].number:int.value =1; How to write value into number:int correctly from javascript? Many thanks, JL.