lovecoding
/
VIP28


			
				
					
						
						
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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">111111111</div>
  <p id="p1">22222222</p>
  <ul id="ul1">
    <li id="li1">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)//节点类型
    console.log(div1.nextSibling)// 下一个节点
    console.log(div1.previousSibling)//上一个节点 */
    /*
    document是没有nodeValue的：null
    元素节点是没有nodeValue的：null
    属性节点id的nodeValue：d1
    内容节点的nodeValue：hello HTML DOM
    */

    // 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)//节点名称
    // console.log(p1.nodeName)
    /* 
    元素节点的 nodeName 与标签名相同
    属性节点的 nodeName 与属性名相同
    文本节点的 nodeName #text
    文档节点的 nodeName #document
    */

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

    // console.log(ul1.firstChild)
    // console.log(ul1.lastChild)
    // console.log(ul1.firstElementChild)

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

</html>