Form_for with :onsubmit


hello list

I have a problem with form_for and :onsubmit

this is may code

<% javascript_tag do %> function valor(){ alert('aqui'); } <% end %>

<% form_for :accion, :url=>{:controller=> “accions”, :action=>
“anadir”}, :html=>{:onsubmit=>“valor();”} do |f| %>

<%= f.submit “Go” %>
<%end %>

when I click in buttom nothing happen with javascript function valor(),
I don´t see the alert

this is my html code

but i don´t find the javascript code of javascript_tag

any idea???

thanks for all