為什么顯示的是undefined
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>無標(biāo)題文檔</title>
</head>
<script type="text/javascript">
?var b_code=Navigator.appCodeName;
?var b_name=Navigator.appName;
?
?var b_version=Navigator.appVersion;
?
?var b_plat=Navigator.platform;
?
?var b_user=Navigator.userAgent;
?document.write(b_code+"<br/>");
?
?document.write(b_name+"<br/>");
?document.write(b_version+"<br/>");
?document.write(b_plat+"<br/>");
?document.write(b_user+"<br/>");
??
</script>
<body>
</body>
</html>
2016-07-25
注意小寫
2016-07-20
navigator
2016-07-17
我暈，大小寫