public function onReorder($fx = null)
    {
        if (is_callable($fx)) {
            if ($this->triggered()) {
                $sortOrders = explode(',', @$_POST['order']);
                $source = @$_POST['source'];
                $newIdx = @$_POST['new_idx'];
                $orgIdx = @$_POST['org_idx'];
                $this->set(function () use ($fx, $sortOrders, $source, $newIdx, $orgIdx) {
                    return call_user_func_array($fx, [$sortOrders, $source, $newIdx, $orgIdx]);
                });
            }
        }
    }