add_action( 'wp_footer', function() {
    if ( is_checkout() && ! is_order_received_page() ) : ?>
        <script type="text/javascript">
        jQuery(function($) {

            // Wait for checkout form submission event
            $('form.checkout').on('checkout_place_order', function() {
                const $button = $('#place_order');

                // Only disable if not already processing
                if (!$button.is(':disabled')) {
                    $button.prop('disabled', true)
                           .css('opacity', '0.6')
                           .text('Processing...');
                }

                return true; // allow normal WooCommerce flow
            });

            // Re-enable the button if validation or payment fails
            $(document.body).on('checkout_error', function() {
                const $button = $('#place_order');
                $button.prop('disabled', false)
                       .css('opacity', '1')
                       .text('Place Order');
            });

        });
        </script>
    <?php
    endif;
});