[Zope] HowTo? onChange assign value to dtml-var

Hello everyone, Does anyone have an example of how to do the following: Let's assume I have a form named form1 with a field named fld_first_name. On any change in the value of that field, I would like to assign the new value to a dtml variable that was previously defined using <!--#call "REQUEST.set('first_name','First Name')"-->. Something like this: <input type="text" name="fld_first_name" onChange='<!--#call "REQUEST.set('first_name',fld_first_name.value)"-->' > I would like to do this so that I can have access to the new value without the SUBMIT button being pressed. Thanks in advance for any help/pointers/code examples provided. -Mark