js判断电脑还是手机

<script type="text/javascript">
//平台、设备和操作系统
var system = {
win : false,
mac : false,
xll : false
};
//检测平台
var p = navigator.platform;
system.win = p.indexOf("Win") == 0;
system.mac = p.indexOf("Mac") == 0;
system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);
//跳转语句
if (system.win || system.mac || system.xll) {//转向后台登陆页面
/* window.location.href = "login.jsp"; */
} else {


/* window.location.href = "wapLojin.jsp";
 */ }
</script>