输入时强制WooCommerce邮政编码字段大写

document.addEventListener('DOMContentLoaded', function() {
    const postalCodeInput = document.querySelector('.woocommerce-checkout .form-row-first input[name="billing_postcode"]');
    if (postalCodeInput) {
        postalCodeInput.addEventListener('input', function() {
            this.value = this.value.toUpperCase();
        });
    }
});

add_filter('woocommerce_checkout_fields', 'force_postal_code_uppercase');
function force_postal_code_uppercase($fields) {
    if (isset($fields['billing']['billing_postcode'])) {
        $fields['billing']['billing_postcode']['value'] = strtoupper($_POST['billing_postcode']);
    }
    return $fields;
}