在我的示例中，我有一个带有模板字段的GridView，它包含一个DropDown菜单和一个TextBox。JavaScript中的OnLoad事件将TextBox的显示样式设置为"none"。在GridView的OnRowDataBound事件中设置DropDown的OnChange事件，并调用JavaScript函数将TextBox的显示样式设置为所需的样式。
在我的示例中，仅当DropDown的选定索引为"1"时才显示TextBox。
我已经在我的代码中完成了这一切-请参考：网格视图ID="GridView1"：

<Columns>
    <asp:TemplateField HeaderText="Order Status">
        <ItemTemplate>
           <asp:DropDownList ID="ddlOrderStatus" runat="server" Width="104px" ToolTip="Select order status">
            </asp:DropDownList><br />
             <asp:TextBox ID="txtShipTrackNo" runat="server" 
      Width="100px" Text='<%# Eval("sct_order_docket_id") %>'></asp:TextBox>
</ItemTemplate>
    </asp:TemplateField>
</Columns>

<script type="text/javascript">
var TargetBaseControl = null;
window.onload = function() {
    try {
    //get target base control.
    TargetBaseControl = document.getElementById('<%= this.GridView1.ClientID %>');
    for (var rowId = 1; rowId < TargetBaseControl.rows.length; ++rowId) {
    var txtShip = TargetBaseControl.rows[rowId].cells[0].getElementsByTagName("input")[0];
    txtShip.style.display = "none";
        }
    }
    catch (err) {
        TargetBaseControl = null;
    }
}

function selectCheck(rowid) 
{
     TargetBaseControl = document.getElementById('<%= this.GridView1.ClientID %>');
     var ddlStatus = TargetBaseControl.rows[rowid].cells[0].getElementsByTagName("select")[0];
     var txtShip = TargetBaseControl.rows[rowid].cells[0].getElementsByTagName("input")[0];
     txtShip.style.display = "none";
     if (ddlStatus.selectedIndex == '1') {
         txtShip.style.display = "block";
     }         
}

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList ddlStatus = (DropDownList)e.Row.FindControl("ddlOrderStatus");
        string strFunc = string.Format("return selectCheck('{0}')", e.Row.RowIndex + 1);  
        ddlStatus.Attributes.Add("onchange", strFunc);
    }
}