about ajax documentation issue

class HomepagePresenter extends \Nette\Application\UI\Presenter
{
    /**
     * This method returns data for the list.
     * Usually this would just request the data from a model.
     * For the purpose of this example, the data is hard-coded.
     * @return array
     */
    private function getTheWholeList()
    {
        return [
            'First',
            'Second',
            'Third'
        ];
    }

    public function renderDefault()
    {
        if (!isset($this->template->list)) {
            $this->template->list = $this->getTheWholeList();
        }
    }

    public function handleUpdate($id)
    {
        $this->template->list = $this->isAjax()
                ? []
                : $this->getTheWholeList();
        $this->template->list[$id] = 'Updated item';
        $this->redrawControl('itemsContainer');
    }
}

<ul n:snippet="itemsContainer">
    {foreach $list as $id => $item}
    <li n:snippet="item-$id">{$item} <a class="ajax" n:href="update! $id">update</a></li>
    {/foreach}
</ul>

<li n:snippet="item-$id">{$item} <a class="ajax" n:href="update!">update</a></li>