.NET在后置代码中输入JS提示语句（背景不会变白）
Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('用户名或密码错误！');</script>");
Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('用户名或密码错误！');</script>");
