使用js实现内容可互换式菜单

<SCRIPT LANGUAGE="JavaScript">
<!--
sitems = 1;               

function move(fbox,tbox) {
for(var i=0; i<fbox.options.length; i++) {
if(fbox.options[i].selected && fbox.options[i].value != "") {
var no = new Option();
no.value = fbox.options[i].value;        
no.text = fbox.options[i].text;          
tbox.options[tbox.options.length] = no;  
fbox.options[i].value = "";              
fbox.options[i].text = "";               
   }
}
BumpUp(fbox);                            
if (sitems) SortD(tbox);                 
}

function BumpUp(box)  {
for(var i=0; i<box.options.length; i++) {
if(box.options[i].value == "")  {        
for(var j=i; j<box.options.length-1; j++)  {
box.options[j].value = box.options[j+1].value;
box.options[j].text = box.options[j+1].text;  
}
var ln = i;break;                             
   }
}
if(ln < box.options.length)  {                
box.options.length -= 1;
BumpUp(box);
   }
}

function SortD(box)  {
var temp_opts = new Array();
var temp = new Object();
for(var i=0; i<box.options.length; i++)  {  
temp_opts[i] = box.options[i];              
}
for(var x=0; x<temp_opts.length-1; x++)  {
for(var y=(x+1); y<temp_opts.length; y++)  {
if(temp_opts[x].text > temp_opts[y].text)  {
temp = temp_opts[x].text;                   
temp_opts[x].text = temp_opts[y].text;      
temp_opts[y].text = temp;                   
temp = temp_opts[x].value;                  
temp_opts[x].value = temp_opts[y].value;    
temp_opts[y].value = temp;
      }
   }
}
for(var i=0; i<box.options.length; i++)  {
box.options[i].value = temp_opts[i].value;
box.options[i].text = temp_opts[i].text;
   }
}
//-->
</script>

<form ACTION="" METHOD="POST">
<table border="0">
<tr>
<td><select multiple size="8" name="list1">
<option value="l1">数学系</option>
<option value="l2">英语系</option>
<option value="l3">物理系</option>
<option value="l4">日语系</option>
</select></td>
<td>
<input type="button" value="添加" οnclick="move(this.form.list1,this.form.list2)" name="B1"><br>
<input type="button" value="删除" οnclick="move(this.form.list2,this.form.list1)" name="B2">
</td>
<td><select multiple size="8" name="list2">
<option value="r1">自动化系</option>
<option value="r2">电子工程系</option>
<option value="r3">信息管理系</option>
<option value="r4">计算机系</option>
</select></td>
</tr>
</table>
</form>