jquery允许跨越获取cookie

 $.ajax({
   url:url,
   type: "get",
   //这里是重点
   xhrFields: { //允许添加cookie
     withCredentials: true
   },
   dataType: "json",
   data:data,
   success:function(res){},
   error:function(err){
     console.log(err)
   }
})