<html>
<head>
<script type="text/javascript">
var txt=""
function message()
{
try
adddlert("Welcome guest!")
}
catch(err)
txt="本页中存在错误。\n\n"
txt+="错误描述：" + err.description + "\n\n"
txt+="点击“确定”继续。\n\n"
alert(txt)
</script>
</head>
<body>
<input type="button" value="查看消息" onclick="message()" />
</body>
</html>