Form validation using RJS

Rails
1

Hi
I have a form as below

<%= form_remote_tag :update => “update_sd_resolution_ui”,
:url => { :action => ‘sd_resolution_save’,
:id => @sd_ticket.id,
:sd_resolution_id=>@sd_resolution_id},
:class => ‘itilform’%>

</table

<%= end_form_tag %>

HERE HOW CAN I CHECK Hr field contains only numbers .How can i implement
this using RJS.Say forexample can i call a javascript function for form
checking from
form_remote_tag above?

Sijo

Hr: <%= text_field :sd_resol, "hours", "size" => 2 %>