您可以使用以下代码找出分配给给定挂钩的操作：

function print_filters_for( $hook = \'\' ) {
    global $wp_filter;
    if( empty( $hook ) || ! array_key_exists( $hook, $wp_filter ) ) {
        return;
    }

    print \'<pre>\';
    print_r( $wp_filter[$hook] );
    print \'</pre>\';
}

<form>
    <h1> My form <h1>
    <input type="text" />
    <?php do_action( \'woocommerce_checkout_after_customer_details\' ); ?>
    print_filters_for( \'woocommerce_checkout_after_customer_details\' );
</form>