$.ajax({
                      url: '@Url.Action("Login")',
                      //data: { "selectedIDs": _list },  
                      data: {
                          name: username,
                          pwd: password
                      },
                      dataType: "json",
                      type: "POST",
                      traditional: true,

                  });

 ContentResult content = new ContentResult();

                content.Content = string.Format("<script type='text/javaScript'>alert(\"用户名错误！\");</script>");

                return content;