lovecoding
/
VIP30


			
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							<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="div1">11111111111</div>
  <p id="p1">222222222</p>
  <ul id="ul1">
    <li>1</li>
    <li>2</li>
    <li>3</li>
  </ul>
  <script>
    var div1 = document.getElementById('div1')
    var p1 = document.getElementById('p1')
    var ul1 = document.getElementById('ul1')
    console.log(div1)

    console.log(div1.nodeType)
    console.log(div1.nextSibling) //下一个节点
    console.log(div1.previousSibling) //上一个节点

    /* 
      documentt 是没有nodevalue   是null
      元素节点也没有nodevalue 
      属性节点id的nodevalue是 
      内容节点的nodevalue就是内容 
    */

    console.log(div1.nodeValue)

    console.log(div1.nextElementSibling)//下一个元素节点
    console.log(div1.previousElementSibling)//上一个元素节点

    console.log(div1.nodeName)//div
    console.log(p1.nodeName) //P

    /* 
      元素节点 nodeName 与标签名相同
      属性节点 nodeName  与属性名相同
      文本节点 nodeName  #text
      文档节点 nodeName  #document
    */

    function next(elem){
      do{
        elem = elem.nextSibling
      } while(elem.nodeType != 1)
      return elem
    }
    console.log(next(p1))

    console.log(div1.firstChild)
    console.log(ul1.lastChild)
    console.log(ul1.firstElementChild)
    console.log(ul1.lastElementChild)


    function first(elem){
      elem = elem.firstChild
      if(elem.nodeType != 1){
        elem = next(elem)
      }
      return elem
    }
    console.log(first(ul1))
  </script>
</body>
</html>