Success in Observe field

Rails
1

Hi,
How to call javascript function using success in observe field .

  <%= observe_field (ha.id,
      :frequency => 0.5,
      :update => "article_list_#{ha.id}",
      :url => {:action => :auto_complete_for_article_title, :id =>

ha.id},
:with => “‘article=’+ escape(value)”,
:success => “close_title(#{ha.id})”)%>

In javascript :
function close_title(div_id){
document.getElementById(‘article_list_’+div_id).style.display=“block”;
}

I want to call close_title function for every success ie. status 200 OK
.
let me know if any there are any alternatives if wrong

thanks,
sri…