Question

我刚接触使用C＃和ASP.NET我试图创建一个注册表单，其中包含<asp:DropDownList>即时通讯试图捕获OnSelectedIndexChange是否有效但我什么也没有得到任何响应。< / p>

这是 signup.aspx

<form id="signupform" runat="server">
    <asp:TextBox runat="server" ID ="firstname" class="form-control" type="text"  placeholder="First Name" style="width: 168px;" pattern = "[a-zA-Z][a-zA-Z ]{2,20}" required="true"/>
    <asp:TextBox runat="server" class="form-control" type="text" value="" placeholder="Middle Name" style="width: 168px;position: relative;margin-top: -50px;margin-left: 192px;" pattern = "[a-zA-Z][a-zA-Z ]{2,20}" required="true"/>
    <asp:TextBox runat="server" class="form-control" type="text"  value="" placeholder="Last Name" pattern = "[a-zA-Z][a-zA-Z ]{2,20}" required="true"/>
    <asp:DropDownList runat="server" ID="month" AutoPostBack="true" OnSelectedIndexChanged ="Month_Selected" class="form-control" style="width: 115px;" required>
        <asp:ListItem Value ="" Text="Month" Selected ="true" Disabled ="true"></asp:ListItem>
        <asp:ListItem Value ="January" Text ="January"></asp:ListItem>
        <asp:ListItem Value ="February" Text ="February"></asp:ListItem>
        <asp:ListItem Value ="March" Text ="March"></asp:ListItem>
        <asp:ListItem Value ="April" Text ="April"></asp:ListItem>
        <asp:ListItem Value ="May" Text ="May"></asp:ListItem>
        <asp:ListItem Value ="June" Text ="June"></asp:ListItem>
        <asp:ListItem Value ="July" Text ="July"></asp:ListItem>
        <asp:ListItem Value ="August" Text ="August"></asp:ListItem>
        <asp:ListItem Value ="September" Text ="September"></asp:ListItem>
        <asp:ListItem Value ="October" Text ="October"></asp:ListItem>
        <asp:ListItem Value ="November" Text ="November"></asp:ListItem>
        <asp:ListItem Value ="December" Text ="December"></asp:ListItem>
     </asp:DropDownList>
    //other personal input infos
</form>

以及 signup.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;


public partial class signup : System.Web.UI.Page
{
   protected void Page_Load(object sender, EventArgs e)
   {

   }

   protected void Month_Selected(object sender, EventArgs e)
  {

    Response.Write("working");
   }

}

请帮助我不知道出了什么问题，我试着查看其他问题，但没有一个问题。

更新1。

通过提交表单，我可以从DropDownList获取值，但OnSelectedIndexChange仍无法正常工作

并且控制台中也没有错误。

Answer 1

您可以使用ClientScript.RegisterClientScriptBlock()方法替代ClientScript.RegisterStartupScript()：

protected void Month_Selected(object sender, EventArgs e)
{
    ClientScript.RegisterClientScriptBlock(this.Page, GetType(), "alert", "alert('working');", true);
}

如果您有ScriptManager个实例（即<asp:ScriptManager>），则可以使用ScriptManager.RegisterStartupScript()方法：

protected void Month_Selected(object sender, EventArgs e)
{
    ScriptManager.RegisterStartupScript(this, typeof(string), "alert", "alert('working');", true);
}

或使用Response.Write手动编写script代码：

if (!string.IsNullOrEmpty(month.SelectedValue))
{
    Response.Write("<script>alert('working');</script>");
}

请注意，您需要服务器端表单标记（即<form runat="server">...</form>才能成功执行脚本。

Answer 2

您可以在字符串中传递值或文本。然后在警报中输出它，如下所示。

    protected void Month_Selected(object sender, EventArgs e)
{
    string wildchild = month.SelectedItem.Text + " - " + month.SelectedItem.Value;
    ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('" + wildchild + "');", true);
}

Answer 3

你可以试试这个

   Response.Write("<script> alert('Working')</script>");

DropDownList OnSelectedIndexChange不起作用

3 个答案: