<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head>
<body>
<form name="form1" method="post" action="">
<select name="sel">
<option value="123">123</option>
<option value="234">234</option>
<option value="345">345</option>
</select>
</form>
<script language="JavaScript">
document.form1.sel.onchange=fun;
function fun(){
alert("this is a test");
}
</script>
</body>
</html>