遍历子元素

var iterator = document.createNodeIterator(document.body, NodeFilter.SHOW_ELEMENT, null, false)
var node = iterator.nextNode()
while (node !== null) {
  console.log(node.tagName)
  node = iterator.nextNode()
}

　或：

var iterator = document.createTreeWalker(document.body, NodeFilter.SHOW_ELEMENT, null, false)
var node = iterator.firstChild()
while (node !== null) {
  console.log(node.tagName)
  node = iterator.nextSibling()
}