JAVASCRIPT 实现增加和删除Select元素

<script type="text/javascript"> //清除选择选项 function cleanValue(cleanSelect,descSelect,isRemove){  var srcSel=  document.getElementById(cleanSelect);  var descSel=document.getElementById(descSelect);    var count=srcSel.length;    for(var i=0;i<count;i++){     if(srcSel.options[i].selected){     if(isRemove){       var isExists=false;       for(var j=0;j<descSel.length;j++){        if(parseInt(descSel.options[j].value)==parseInt(srcSel.options[i].value)){         isExists=true;         break;        }       }       if(!isExists){        descSel.options[descSel.length]= new Option(srcSel.options[i].text,srcSel.options[i].value);        }     }     srcSel.remove(srcSel.selectedIndex);     i--;     count--;  } }  }//添加选项function addSelect(srcSelect,descSelect,isRemove){ var srcSel = document.getElementById(srcSelect); var descSel = document.getElementById(descSelect); var count=srcSel.length; for( var i=0;i<count;i++){     if(srcSel.options[i].selected){   descSel.options[descSel.length]= new Option(srcSel.options[i].text,srcSel.options[i].value);   if(isRemove){       srcSel.remove(srcSel.selectedIndex);       count--;       i--;     }  } }}function getSelectAllValue(srcSelect,descSelect){ var srcSel = document.getElementById(srcSelect); var pv=document.getElementById(descSelect); var value=""; for( var i=0;i<srcSel.length;i++){     value+=srcSel.options[i].value+","; } if(value.length>0){  pv.value=value.substring(0,value.length-1); }} </script>    <tr bgcolor="#FFFFFF">   <td>奖品池:</td>   <td>    <select id="awardList" name="awardList" size="5" style="width: 156px">     <c:forEach var="award" items="${awardList}">      <option value="${award.id }">${award.award_name }</option>     </c:forEach>    </select>   </td>   <td>    <b style="text-align: center;">添加奖品</b>    <ol>     <li><a href="javascript:void(0);" onclick="addSelect('awardList','addAwardList',false)">拷贝></a></li>     <li><a href="javascript:void(0);" onclick="addSelect('awardList','addAwardList',true)">移>></a></li>     <li><a href="javascript:void(0);" onclick="cleanValue('addAwardList','awardList',false)"> 删除右 </a></li>     <li><a href="javascript:void(0);" onclick="cleanValue('addAwardList','awardList',true)"> <<移 </a></li>    </ol>   </td>   <td>    <select id="addAwardList" name="addAwardList" size="5" style="width: 156px">    </select>   </td>  </tr>