c# - 下拉菜单 SelctIndexChange 未按预期工作

Question

//master.cs     
protected void ddlLanguage_SelectedIndexChanged(object sender, EventArgs e)
    {
    //alert box
            string message = "Some Content of the Site are only in English. Do you want to continue?";
            System.Text.StringBuilder sb = new System.Text.StringBuilder();
            sb.Append("return confirm('");
            sb.Append(message);
            sb.Append("');");
            Page.ClientScript.RegisterOnSubmitStatement(this.GetType(), "alert", sb.ToString());
       //alert end
            //Sets the cookie that is to be used by Global.asax
            HttpCookie cookie = new HttpCookie("CultureInfo");
            cookie.Value = ddlLanguage.SelectedValue;
            Response.Cookies.Add(cookie);

            //Set the culture and reload the page for immediate effect. 
            //Future effects are handled by Global.asax
            Thread.CurrentThread.CurrentCulture = new CultureInfo(ddlLanguage.SelectedValue);
            Thread.CurrentThread.CurrentUICulture = new CultureInfo(ddlLanguage.SelectedValue);
            Server.Transfer(Request.Path);
    }

//master  Page
<asp:DropDownList ID="ddlLanguage" class="langpnl" runat="server" AutoPostBack="True" 
        OnSelectedIndexChanged="ddlLanguage_SelectedIndexChanged">
        <asp:ListItem Value="en-US">Eng</asp:ListItem>
        <asp:ListItem Value="es-ES">Esp</asp:ListItem>
    </asp:DropDownList>

每当用户从英语更改为西类牙语时，我想显示一个警报框。 这是一种奇怪的行为，此代码不起作用，它没有向我显示有关所选索引更改的任何警报框，但如果我将警报框代码粘贴到页面加载事件中，它就会起作用。页面加载与此有什么关系吗？ 其次，是否可以记住答案，即如果用户选择了一个表示“记住我”的复选框，我应该记住用户在整个 session 中是否选择了"is"或“否”。 关于第二个问题的任何建议都会有帮助。但请帮我找出上述代码未按预期工作的原因。

Answer 1

在您的dropdownSelected索引更改事件中尝试以下代码以显示警报框

if (!ClientScript.IsStartupScriptRegistered("JSScript"))
            {
                //give the exception details in a alert box
                string sb = string.Format(@"<script>alert('{0}');</script>'", "Message to be shown");
                ClientScript.RegisterStartupScript(this.GetType(), "JSScript", sb);
            }