WooCommerce restrict only Shipping State for selected country

functions.php

add_action( 'wp_footer', 'webtoffee_checkout_shipping_filter_it_states' );
   
function webtoffee_checkout_shipping_filter_it_states() {
   if ( ! is_checkout() ) {
      return;
   }
   ?>
      
   <script>
   jQuery(document).ready(function($) {
 
      $(document.body).on('country_to_state_changed', function() {
 
         var $shipping_country = $('#shipping_country');
 
         var new_shipping_state = '';
 
         switch($shipping_country.val()) {
            case 'IT':
               new_shipping_state =  {'TV': "Treviso", "CA": "Carità", "Cs": "Castrette"};
               break;
         }
 
             if( ! $.isEmptyObject(new_shipping_state)) {
                
                var optionsAsString = "";
                for (var key in new_shipping_state) {
                    optionsAsString += "<option value='" + key + "'>" + new_shipping_state[key] + "</option>";
                }
                $( 'select[name="shipping_state"]' ).html( optionsAsString );
                
             } 
 
      });
 
   });  
   </script>
       
   <?php
}