<!DOCTYPE html>
<html>
<head>
<script>
var txt="";
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="本页有一个错误。\n\n"; //文本换行\n\n
txt+="错误描述：" + err.message + "\n\n";
txt+="点击确定继续。\n\n";
alert(txt);
}
}
</script>
</head>
<body>
<!--两种类型的按钮-->
<input type="button" value="查看消息" onclick="message()">
<button type="button" onclick="message()">Click here</button>
</body>
</html>