// Assign even and odd classes to nav bar menu items

add_action('wp_enqueue_scripts', 'add_my_code');

function add_my_code() {
    add_action( 'print_footer_scripts', 'my_footer_script' );
}

function my_footer_script() { ?>
    <script type="text/javascript">
        jQuery(document).ready(function($) {
		$("#menu-standaard > li:nth-child(odd)").addClass("odd");
        	$("#menu-standaard > li:nth-child(even)").addClass("even");
        });
    </script>
<?php }