xiuquanxu
xiuquanxu
I think the root node for delegated events should be on the root(id is app div) instead of document.
Universal render method is different client render method. client render method will clean nodes` element.textContent = "";` I am not sure whether universal render need add this logic. 
emmm, I think cleanup is inner logic. It should not implement custom by users. Override render method is good way.