The JS code problem is solved by the following code

<!DOCTYPE html>
<html>
 <head>
  <title> new document </title>  
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>   
  <script type="text/javascript">  
     window.onload = function(){  //
        Highlight();
     }  
     
     function Highlight(){
         var tbody = document.getElementById("table").lastChild;    //tabletr
        trs = tbody.getElementsByTagName("tr");   
        for(var i =1;i<trs.length;iPP){    
            trs[i].onmouseover = function(){
                this.style.backgroundColor ="-sharpf2f2f2";
            } 
            trs[i].onmouseout = function(){
                this.style.backgroundColor ="-sharpfff";
            } 
        }  
     }
          
     function addOne(obj){ 
        var tbody = document.getElementById("table").lastChild;  
        var tr = document.createElement("tr");  
         
         var td = document.createElement("td");
         td.innerHTML = "<input type="text"/>";
         tr.appendChild(td);
         
         td = document.createElement("td");     
         td.innerHTML = "<input type="text"/>";
         tr.appendChild(td);
         
         td = document.createElement("td");    
         td.innerHTML = "<a href="javascript：;" onclick="deleteRow(this)"></a>";
         tr.appendChild(td);   
         
         tbody.appendChild(tr);   //tabletrtr
        Highlight();
        }

     function deleteRow(obj){
        var tbody = document.getElementById("table").lastChild;   //tabletrtr
        var tr = obj.parentNode.parentNode;
         tbody.removeChild(tr);
     }


  </script> 
 </head> 
 <body> 
       <table border="1" width="50%" id="table">
       <tr>
        <th></th>
        <th></th>
        <th></th>
       </tr>  

       <tr>
        <td>xh001</td>
        <td></td>
        <td><a href="javascript：;" onclick="deleteRow(this)"></a></td>
       </tr>

       <tr>
        <td>xh002</td>
        <td></td>
        <td><a href="javascript：;" onclick="deleteRow(this)"></a></td>
       </tr>  

       </table>
       <input type="button" value="" onclick="addOne()" />
 </body>
</html>

var tbody = document.getElementById ("table"). LastChild; the last child node of the table node where id is table is the last tr node, isn"t it? Isn"t there only one? Why is it an array?

Css javascript html
Mar.20,2021

< tbody > tag to learn about

http://www.w3school.com.cn/ta.

the Chinese translation of MDN is not finished yet, but it is enough to understand w3school.

https://developer.mozilla.org.

Hello, does not return an array node. Instead, it is the tbody node label under table.
Modern browsers add this tag to adapt to the W3C standard.

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MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3c49c-4088b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3c49c-4088b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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