可上移下移的下拉选择框

答案：<html>
<head>
<title>下拉选择框</title>
</head>
<script>
function move(fbox,tbox) {
var i = 0;
if(fbox.value != "") {
var no = new Option();
no.value = fbox.value;
no.text = fbox.value;
tbox.options[tbox.options.length] = no;
fbox.value = "";
   }
}
function remove(box) {
for(var i=0; i<box.options.length; i++) {
if(box.options[i].selected  &&  box.options[i] != "") {
box.options[i].value = "";
box.options[i].text = "";
   }
}
BumpUp(box);
} 
function BumpUp(abox) {
for(var i = 0; i < abox.options.length; i++) {
if(abox.options[i].value == "")  {
for(var j = i; j < abox.options.length - 1; j++)  {
abox.options[j].value = abox.options[j + 1].value;
abox.options[j].text = abox.options[j + 1].text;
}
var ln = i;
break;
   }
}
if(ln < abox.options.length)  {
abox.options.length -= 1;
BumpUp(abox);
   }
}
function Moveup(dbox) {
for(var i = 0; i < dbox.options.length; i++) {
if (dbox.options[i].selected  &&  dbox.options[i] != ""  &&  dbox.options[i] != dbox.options[0]) {
var tmpval = dbox.options[i].value;
var tmpval2 = dbox.options[i].text;
dbox.options[i].value = dbox.options[i - 1].value;
dbox.options[i].text = dbox.options[i - 1].text
dbox.options[i-1].value = tmpval;
dbox.options[i-1].text = tmpval2;
      }
   }
}
function Movedown(ebox) {
for(var i = 0; i < ebox.options.length; i++) {
if (ebox.options[i].selected  &&  ebox.options[i] != ""  &&  ebox.options[i+1] != ebox.options[ebox.options.length]) {
var tmpval = ebox.options[i].value;
var tmpval2 = ebox.options[i].text;
ebox.options[i].value = ebox.options[i+1].value;
ebox.options[i].text = ebox.options[i+1].text
ebox.options[i+1].value = tmpval;
ebox.options[i+1].text = tmpval2;
      }
   }
}
</script>
</head>
<body>
<form ACTION="" METHOD="POST">
  <table align="center">
    <tr>
<td>
<input type="text" name="list1" value="">
</td>
<td>
<input type="button" value="添加新值" onclick="move(this.form.list1,this.form.list2)" name="B1"><br>
<input type="button" value="删除选中" onclick="remove(this.form.list2)" name="B2"><br><br>
<input type="button" value="向上移动" onclick="Moveup(this.form.list2)" name="B3"><br>
<input type="button" value="向下移动" onclick="Movedown(this.form.list2)" name="B4">
</td>
<td>
<select multiple size=7 name="list2">
<option value="2">Baidu.com</option>
<option value="3">Sohu.com</option>
</select>
</td>
</tr>
</table>
</form>
</body>
</html>
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