向客户端注册脚本

protected void btnLogin_Click(object sender, EventArgs e)
    {
        ClientScriptManager CS = Page.ClientScript;
        CS.RegisterStartupScript(this.GetType(), "postTrue", "<script language='javascript' type='text/javascript'>window.alert('这是通过客户端校验后，从后台代码发来的提示！')</script>");
    }