<select name="Ddl1:ddlMain" id="Ddl1_ddlMain" onchange="javascript:LoadChild(this.value);" style="width:100">
<option value="安庆|aqg,蚌埠|bengbu,亳州|bozhou,阜阳|buyang,巢湖|caohu,池州|chizhou,滁州|chuzhou,海北|haibei,合肥|hfe,淮南|huainan,马鞍山|maanshan,六安|niuan,苏州|suzhou,铜陵|tongling,黄山|txn,芜湖|wuhu,宣城|xuancheng">安徽</option>
<option value="北京|pek">北京</option>
<option value="重庆|cqq">重庆</option>
<option value="福州|foc,龙岩|longyan,南平|nanping,宁德|ningde,莆田|putian,泉州|quanzhou,三明|sanming,西宁|xmn,漳州|zhangzhou">福建</option>
<option value="广州|can,潮州|chaozhou,东莞|dongguan">宜昌</option>
</select>
<select name="sel" style="width:100" onchange="alert(this.value)"></select>
<script language="JavaScript">
<!--
function LoadChild(theV)
{
var str = theV.split(",");
var s="";
for(var i=0;i<str.length;i++)
{
s = str[i].split("|");
oOptions=new Option(s[0],s[1]);
sel.add(oOptions);
}
}
//-->
</script>
<option value="安庆|aqg,蚌埠|bengbu,亳州|bozhou,阜阳|buyang,巢湖|caohu,池州|chizhou,滁州|chuzhou,海北|haibei,合肥|hfe,淮南|huainan,马鞍山|maanshan,六安|niuan,苏州|suzhou,铜陵|tongling,黄山|txn,芜湖|wuhu,宣城|xuancheng">安徽</option>
<option value="北京|pek">北京</option>
<option value="重庆|cqq">重庆</option>
<option value="福州|foc,龙岩|longyan,南平|nanping,宁德|ningde,莆田|putian,泉州|quanzhou,三明|sanming,西宁|xmn,漳州|zhangzhou">福建</option>
<option value="广州|can,潮州|chaozhou,东莞|dongguan">宜昌</option>
</select>
<select name="sel" style="width:100" onchange="alert(this.value)"></select>
<script language="JavaScript">
<!--
function LoadChild(theV)
{
var str = theV.split(",");
var s="";
for(var i=0;i<str.length;i++)
{
s = str[i].split("|");
oOptions=new Option(s[0],s[1]);
sel.add(oOptions);
}
}
//-->
</script>
{
var str = theV.split(",");
var s="";
for(var j=0;j<sel.children.length;j++)
sel.remove(i)
for(var i=0;i<str.length;i++)
{
s = str[i].split("|");
oOptions=new Option(s[0],s[1]);
sel.add(oOptions);
}
}
//-->
{
for(var i=sel.length;i>-1;i--)
{
sel.options[i]=null
} var str = theV.split(",");
var s="";
for(var i=0;i<str.length;i++)
{
s = str[i].split("|");
oOptions=new Option(s[0],s[1]);
sel.add(oOptions);
}
}
--------------------
<select id="o"><option>dd</option><option>bb</option><option>dd</option><option>bb</option><option>dd</option><option>bb</option></select>
<input type="button" onclick="clearSelect()"><script language="javascript">
<!--
function clearSelect()
{
for(var i = o.options.length-1 ;i>=0;i--)
{
o.remove(i);
}
}
//-->
</script>