Can any one give me answer about remote_form_for..?

Can any one give me answer???

I want to check whether textfield is empty or not at onsubmit event of
form, but it is not working.
Can any one tell me how to check empty textfield on remote_form_for’s
onsubmit event???

my code is --------------->

<%remote_form_for(:comments, @comment, :url => @commentUrl, :html =>
{:method => :post, :onsubmit => ‘if ($(“comments_comment”).value == “”)
{showNotificationMessage(“Please enter comment”, Notification.Error,
comments_comment); return false;}’}) do |f| %>
<%= f.text_area “comment”, :rows => 2,

  <%=submit_to_remote f, "Add comment",
    :url => @commentUrl,
    :update => { :success => divID, :failure => divID }%>

‘onsubmit’ is not excuted during form submit.
Any one can help me.