Register a menu onclick function

I am trying to add this in an abc.php file where add_footer_menu() is a onclick function. This is showing me the “Menu added.” but menu is actually not generating.

<script type="text/javascript">
				function add_footer_menu(){
		        		<?php
		        		add_action( 'after_setup_theme', 'register_my_footer_menu' );
		        		function register_my_footer_menu() {
		        			register_nav_menu( 'abc', 'abc menu');
		        		}
		        		?>
		        		document.getElementById("notify_menu").innerHTML = "Menu added. Go to Themes > Menus to add menu items.";
	        		}
			</script>