JS编程练习：封装insertAfter函数(功能类似于系统insertBefor)

那么insertAfter()要实现的功能：在指定的子节点后面插入新的子节点；

 1 <body>
 2     <div>
 3         <p></p>
 4         <span></span>
 5         <em></em>
 6         <i></i>
 7     </div>
 8 
 9 <script type="text/javascript">
10     Element.prototype.insertAfter = function(targetNode,afterNode){
11         var beforNode = afterNode.nextElementSibling;
12 
13         if(beforNode == null){
14             this.appendChild(targetNode);
15         }else{
16             this.insertBefore(targetNode,beforNode);
17         }
18     }
19 
20     var div = document.getElementsByTagName('div')[0];
21     var span = document.getElementsByTagName('span')[0];
22     var i = document.getElementsByTagName('i')[0];
23     var a = document.createElement('a');
24 </script>
25 </body>

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