Flash works on the server-side, not on the client side. I *think* (if someone else knows otherwise, please speak up) what most do is use replace_html to update the content of the html element that wraps the flash message. So if you have this:
<div id="notice"><%=h flash[:notice] %></div>
Then you would do this:
render :update do |page| page[:notice].replace_html "insert message here" end
