js简单实现Select互换数据的方法

<title>两个Select互换数据，简单实用</title>
<script language="JavaScript">
var MainSel = null;
var SlaveSel = null;
var Item_ = new Array();function DoAdd(){
 var this_sel = null;
 for(var i=0;i<MainSel.options.length;i++){
  this_sel = MainSel.options[i];
  if(this_sel.selected){
   SlaveSel.appendChild(this_sel);
   i--;
  }
 }
 sort_Main(SlaveSel);
}function DoDel(){
 var this_sel = null;
 for(var i=0;i<SlaveSel.options.length;i++){
  this_sel = SlaveSel.options[i];
  if(this_sel.selected){
   MainSel.appendChild(this_sel);
   i--;
  }
 }
 sort_Main(MainSel);
}function sort_Main(the_Sel){
 var this_sel = null;
 for(var i=0;i<Item_.length;i++){
  for(var j=0;j<the_Sel.options.length;j++){
   this_sel = the_Sel.options[j];
   if(this_sel.value==Item_[i][0] && this_sel.text==Item_[i][1]){
    the_Sel.appendChild(this_sel);
   }
  }
 }
}window.onload=function(){
 MainSel = select1;
 SlaveSel = select2;
 MainSel.ondblclick=DoAdd;
 SlaveSel.ondblclick=DoDel;
 var this_sel = null;
 for(var i=0;i<MainSel.options.length;i++){
  this_sel = MainSel.options[i];
  Item_.push(new Array(this_sel.value,this_sel.text));
 }
}
</script>
<table width="300" border="0" cellspacing="0" cellpDoAdding="0" align="center">
 <tr>
 <td width="45%" align="center">
 <select id="select1" size="5" multiple style="width: 100px">
  <option value="111">111</option>
  <option value="222">222</option>
  <option value="333">333</option>
  <option value="444">444</option>
  <option value="555">555</option>
  <option value="666">666</option>
  </select> 
 </td>
 <td width="10%" align="center">
 <input name="DoAdd" type="button" value=">>" onClick="DoAdd()"><br>
 <input name="DoDel" type="button" value="<<" onClick="DoDel()">
 </td>
 <td width="45%" align="center">
 <select id="select2" size="5" multiple style="width: 100px">
 </select>
 </td>
 </tr>
</table>