辅助完成顺序遍历DOM结构的类型：NodeIterator 和 TreeWalker 1、NodeIterator document.createNodeIterator() nextNode() previousNode() 2、TreeWalker document.createTreeWalker(div,NodeFilter.SHOW_ELEMENT,filter,false) 除了nextNode()和 previousNode()外 parentNode() firstChild() lastChild() nextSibling() previousSibling()