Do you understand what the JSTL is? In fact, it seems like you are even confused about what JSP is. Perhaps
this article can help.
All that JSP, or the JSTL, or any other server-side mechanism can do is to create HTML to send to the browser. Once at the browser, all you've got to work with is HTML, CSS and JavaScript.
If you want to have more than forms and links available to you on the client, you'll need to use JavaScript.