为什么显示的是undefined

源自：8-12 Navigator对象

<html>

<head>

<title>无标题文档</title>

</head>

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>

提问者：jcfc 2016-07-17 09:49