var system ={};

     var p = navigator.platform;

     system.win = p.indexOf("Win") == 0;

     system.mac = p.indexOf("Mac") == 0;

     system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);

     if(system.win||system.mac||system.xll){//如果是电脑跳转到百度

         window.location.href="http://www.baidu.com/";

     }else{  //如果是手机,跳转到谷歌

         window.location.href="http://www.google.cn/";

     }