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/"; 
    }