<script language="javaScript">
function change()
{
if(document.form1.myselect.value=="1") {
alert("您选择了选项1")
}
if(document.form1.myselect.value=="2") {
alert("您选择了选项2");
}
}
</script>
<html>
<body>
<form name="form1">
<select name="myselect" onchange="change()">
<option>请选择</option>
<option value="1">选项一</option>
<option value="2">选项二</option>
</select>
</form>
</body>
</html>