How to block search engines indexing certain AJAX actions

Question

I have a shopping cart which uses AJAX to add/remove items to the cart from an <a> styled as a button which links to an action like /wp-admin/admin-ajax.php?action=shopping_cart&id=16&nonce=123456&type=add.

These links keep getting crawled by search engines - however, since the nonce is different each time, the list of crawl errors keeps growing.

What's the most effective method to prevent search engines from trying to follow the link? I understand that a simple nofollow may not be appropriate for internal links. Alternatively, I am misusing the <a> tag and would another element and a bit of jQuery to follow the admin-ajax.php link be better?

Answer 1

If an ajax call is indexed it compromises the whole purpose of the application. The cause here is that you are making your call using GET instead of POST as suggested: https://codex.wordpress.org/AJAX_in_Plugins

The right way should be along something like :

<?php
add_action( 'admin_footer', 'my_SHOP_javascript' ); // Write our JS below here

function my_SHOP_javascript() { ?>
    <script type="text/javascript" >
    jQuery(document).ready(function($) {

        var data = {
            'action': 'shopping_cart',
            'id': 16,
            'nonce': '12345',
            'type' : 'add'
        };

        jQuery.post(ajaxurl, data, function(response) {
            //YOUR CODE AFTER SUCCESS
        });
    });
    </script> <?php
}