1.获取元素距离顶部的高度

  1. function getOffsetTop(element) {
  2.     var realHeight = element.offsetTop;
  3.     var parentNode = element.offsetParent;
  4.     while (parentNode != null) {
  5.         realHeight += parentNode.offsetTop;
  6.         parentNode = parentNode.offsetParent;
  7.     }
  8.     return realHeight;
  9. }

2.ownerDocument

//获取整个文档的文档节点

3.hasChildNodes()

//返回boolean值