在select1的onchange事件里：
window.Form1.Select2.innerHTML=""
xiang=new Option();
xiang.text="dd"
xiang.value="ff"
window.Form1.Select2.add(xiang);
window.Form1.Select2.innerHTML=""
xiang=new Option();
xiang.text="dd"
xiang.value="ff"
window.Form1.Select2.add(xiang);
<head>
<script>
function check()
{
if(f1.d1.options[0].selected)
{
f1.d2.length=0 f1.d2.options.add(new Option("***白菜***","***白菜***"))
f1.d2.options.add(new Option("***萝卜***","***萝卜***"))
}
else if(f1.d1.options[1].selected)
{
f1.d2.length=0
f1.d2.options.add(new Option("***苹果***","***苹果***"))
f1.d2.options.add(new Option("***桃***","***桃***")) }}
</script>
</head><body><form name="f1" method="POST" action="--WEBBOT-SELF--">
<p><select size="1" name="d1" onchange="check()">
<option selected>***蔬菜***</option>
<option>***水果***</option>
</select><select size="1" name="d2">
<option>***白菜***</option>
<option>***萝卜***</option>
</select></p>
</form></body></html>
<title>New Page 1</title>
<script>
var FiArray=new Array();
var SeArray=new Array();
function initdata()
{
for(var i=0;i<5;i++)
{
FiArray[i]="aaa"+(i+1);
}
for(var i=0;i<5;i++)
{
SeArray[i]="bbb"+(i+1);
}}
function showdata(sou)
{
var obj=document.all("Substr");
//此处先调用一函数清空列表，自己写了
switch(sou.value)
{
case "a":
for(var i=0;i<5;i++)
{
var no=new Option();
no.value=FiArray[i];
no.text=FiArray[i];
obj.options[obj.options.length]=no;
}
break;
case "b":
for(var i=0;i<5;i++)
{
var no=new Option();
no.value=SeArray[i];
no.text=SeArray[i];
obj.options[obj.options.length]=no;
}
break;
default:
break;
}
}
</script>
</head><body onload="initdata();"><form method="POST" action="">
<p><select size="1" name="D1" onchange="showdata(this)">
<option value="a">a</option>
<option value="b">b</option>
</select><select size="1" name="Substr" id="Substr">
</select></p>
</form></body></html>