Wordpress: How can I add url GET parameter to my main menu items

Question

I'm trying to add a URL GET parameter to one of my main menu items in Wordpress(but I don't know how to). So, my approach was to detect a click event on the menu item, then pass a parameter via ajax to my php page which will process value passed as needed. My main questions are, looking at my code, how come is not working? is there a better way of doing this in Wordpress and not rely on javascript?

Here is the javascript:
    <script type="text/javascript">
        $(document).ready(function() {
            $("#menu-item-128").click(function() {
                $.ajax({
                    url: 'homepage.php',
                    type: "GET",
                    data: ({ homeclick = true }),
                    success: function() {
                       alert("success!");
                    }
                });
             });
         });
   </script>

Here is my PHP:
   $homeclick = $_GET['homeclick'];   

   if ( !isset( $_COOKIE['hs_user'] ) ) {
       get_header();
   } elseif (isset( $_COOKIE['hs_user'] ) && $homeclick == true ) {
       get_header();
   } else {
       // Do Something else
       header('Location: homepage-returning-users');        
   }

Answer 1

The filter hook wp_get_nav_menu_items is used to manipulate the Nav Menus. The post_title used in the example is the title of the Menu (Navigation Label), not of the post/page.

Drop this code in your functions.php file, adjust the post_title and ?my_var=test to your needs. Note that better than functions is to create your own plugin.

add_filter( 'wp_get_nav_menu_items','nav_items', 11, 3 );

function nav_items( $items, $menu, $args ) 
{
    if( is_admin() )
        return $items;

    foreach( $items as $item ) 
    {
        if( 'Home' == $item->post_title)
            $item->url .= '?my_var=test';

    }
    return $items;
}