html5判斷瀏覽器來源並跳轉

<script type="text/javascript">
        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){//如果是電腦跳轉到
       alert("請從手機端訪問");
               window.location.href="http://52td.top";  
       }else{  //如果是手機,跳轉到
            //console.log(11111);
            window.location.href="#";  
       }
</script>