js--cookie

   setCookie('g20', 'noshow'); //设置cookie
if(address.indexOf('西藏')==0 && (getCookie('g20') != 'noshow' || getCookie('g20') == null)){
        //执行语句
    }

 $.ajax({
        type:"GET",
        url:"/user.php?a=logout",
        async:false,
        data:"",
        dataType:'json',
        success:function(result){
            delCookie('g20');
        }
     });

//删除cookie
     function delCookie(c_name){
        var exdate=new Date()
         exdate.setDate(exdate.getDate() - 1)
         document.cookie = c_name + '=;path=/;expires=Thu, 01 Jan 1970 00:00:01 GMT';

     }