try
<head>
<script language="javascript">
var banlist = new Array();
banlist[0] = ["精品班","提前班","普通斑"];
banlist[1] = ["普通班"];function changeBan()
{
document.form1.ban.options.length = 0;
var n = document.form1.leixing.selectedIndex;
for (var i=0; i < banlist[n].length; i++)
{
var opt = new Option(banlist[n][i],banlist[n][i]);
document.form1.ban.options.add(opt);
}
}
</script>
</head>
<body onload="changeBan()">
<form name="form1">
<select size="1" name="leixing" onchange="changeBan()">
<option>中级</option>
<option>初级</option>
</select>
<select size="1" name="ban">
</select>
</form>
</body>
<head>
<script language="javascript">
var banlist = new Array();
banlist[0] = ["精品班","提前班","普通斑"];
banlist[1] = ["普通班"];function changeBan()
{
document.form1.ban.options.length = 0;
var n = document.form1.leixing.selectedIndex;
for (var i=0; i < banlist[n].length; i++)
{
var opt = new Option(banlist[n][i],banlist[n][i]);
document.form1.ban.options.add(opt);
}
}
</script>
</head>
<body onload="changeBan()">
<form name="form1">
<select size="1" name="leixing" onchange="changeBan()">
<option>中级</option>
<option>初级</option>
</select>
<select size="1" name="ban">
</select>
</form>
</body>
document.form1.ban.options.add(opt);
to
document.form1.ban.options[i] = opt;
<script language="javascript">
var banlist = new Array();
banlist[0] = ["精品班","提前班","普通斑"];
banlist[1] = ["普通班"];function changeBan()
{
document.form1.ban.options.length = 0;
var n = document.form1.leixing.selectedIndex;
for (var i=0; i < banlist[n].length; i++)
{
var opt = new Option(banlist[n][i],banlist[n][i]);
document.form1.ban.options.add(opt);
}
}
</script>
</head>
<body onload="changeBan()">
<form name="form1">
<select size="1" name="leixing" onchange="changeBan()">
<option>中级</option>
<option>初级</option>
</select>
<select size="1" name="ban" onchange="if(this.options[this.selectedIndex].text=='精品班')a1.disabled=false;else a1.disabled=true">
</select>
<input id=a1 disabled>
</form>
</body>
大家看看:
<head>
<script language="javascript">
var banlist = new Array();
banlist[0] = ["提前班","精品班","普通斑"];
banlist[1] = ["普通班"];function changeBan()
{
document.form1.ban.options.length = 0;
form1.a1.disabled=true
form1.a2.style.visibility="hidden"
var n = document.form1.leixing.selectedIndex;
for (var i=0; i < banlist[n].length; i++)
{
var opt = new Option(banlist[n][i],banlist[n][i]);
document.form1.ban.options.add(opt);
}
}function onchangea1()
{
if(form1.ban.options[form1.ban.selectedIndex].text=='精品班')
{
form1.a1.disabled=false
form1.a2.style.visibility="visible"
}
else
{
form1.a1.disabled=true
form1.a2.style.visibility="hidden"
}
}
</script>
</head>
<body onload="changeBan()">
<form name="form1">
<select size="1" name="leixing" onchange="changeBan()">
<option>中级</option>
<option>初级</option>
</select>
<select size="1" name="ban" onchange="onchangea1()">
</select>
<input id=a1 disabled>
<input id=a2 >
</form>
</body>
</html>
var opt = new Option(banlist[n][i]);