javascript 节点遍历函数

!--NEWSZW_HZH_BEGIN-- 火狐官网上找到的一组函数，相当于treeWalker，有了它可以便利地在IE实现Traversal API 2的所有功效（nextElementSibling，previousElementSibling，firstElementChild，lastElementChild，children）These functions let you find the next sibling, previous sibling, first child, and last child of a given node (element). What makes them unique is that they safely ignore whitespace nodes so you get the real node you"re looking for each time. 火狐官网上找到的一组函数，相当于treeWalker，有