一处定义，可以抓取全局的错误，相当于一个全局的try catch呀。
<html>
<head>
<script type="text/javascript">
onerror=handleErr function handleErr(msg,url,l)
{
var txt=""
txt="本页中存在错误。\n\n"
txt+="错误：" + msg + "\n"
txt+="URL: " + url + "\n"
txt+="行：" + l + "\n\n"
txt+="点击“确定”继续。\n\n"
alert(txt)
return true
} function message()
{
adddlert("Welcome guest!")
}
</script>
</head> <body>
<input type="button" value="查看消息" onclick="message()" />
</body> </html>