[求助]两个文本域之间的互交响应问题，请高手指点，谢谢！

这样实现 是 ASP 写的
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script language="javascript">
 
function addList(){
          
  var thelist=document.form1.leftlist;
  var theText=document.form1.theText.value;
  var theValue=document.form1.theValue.value;
 
  var theOption=new Option(theText,theValue);
  var thePostion=thelist.options.length;
   thelist.options[thePostion] =theOption;
  
}
 function movlist(a,b){
 var folist=document. form1.elements[a];
 var tolist=document. form1.elements[b];
 var theNum= folist.options.selectedIndex;
 
 while(theNum>=0){ var theText=folist.options[theNum].text;
 var theValue=folist.options[theNum].value;
 var newOption=new Option(theText,theValue);
 var theNum2=tolist.options.length; tolist.options[theNum2]=newOption;
 
 folist.options[theNum]=null;
 theNum=folist.options.selectedIndex;  }}
function delLlis(){
     
    var theForm=document.form1; var formNum1=theForm.leftlist.options.selectedIndex;
   if(formNum1>=0){
theForm.leftlist.options[formNum1]=null;

}
  
var formNum2=theForm.rightlist.options.selectedIndex;
if(formNum2>=0){
theForm.rightlist.options[formNum2]=null;

}
}
 
</script></head><body>
<form id="form1" name="form1" method="post">
  <table width="353" border="1" align="center">
    <tr>
      <td width="167" align="center" valign="top"><select name="leftlist" size="10" multiple="MULTIPLE">
        <option value="11">aaaa</option>
        <option value="22">bbb</option>
        <option value="333">ccc</option>
        <option value="444">dddd</option>
        <option value="5555">eeeee</option>
      </select></td>
      <td colspan="2"><p>
        <input name="Submit2" type="button" value="&gt;&gt;"    
   onclick="movlist('leftlist','rightlist')"/>
      </p>
        <p>&nbsp;</p>
        <p>        
          <input name="Submit3" type="button" value="&lt;&lt;" onclick="movlist('rightlist','leftlist')"/>
          </p></td>
      <td width="181" align="center"><p>
        <select name="rightlist" size="10" multiple="multiple" >
        </select>
      </p>      </td>
    </tr>
    
    <tr>
      <td colspan="2" align="center"><p>标签
        </p>
        <p>
          <input name="theText" type="text" maxlength="10" />
        </p></td>
      <td colspan="2" align="center"><p>值
        </p>
        <p>
          <input name="theValue" type="text" maxlength="10"  />
        </p></td>
    </tr>
    <tr>
      <td colspan="3" align="center"><input type="button" name="Submit" value="添加" onclick="addList()"/>
      <td align="center"> <input type="button" name="Submit4" value="删除" onclick="delLlis()"/></td>
    </tr>
  </table>
</form>
</body>
</html>