我在使用JavaScript的asp.net中有一个弹出窗口，我需要在网页上的文本框中显示变量。变量空白，所以我相信我错过了一些东西。我想我错过了document.getElementById中的一些东西要么我应该使用不同的东西，我正在使用它不正确
这是我的JavaScript
<!DOCTYPE html>
<title></title>
<script type = "text/javascript">
function Confirm() {
var confirm_value = document.createElement("INPUT");
confirm_value.type = "hidden";
confirm_value.name = "confirm_value";
var ppn = document.getElementById("<%= pifPassportNbr %>")
var pid = document.getElementById("<%= pifIssueDate.Text %>")
var pil = document.getElementById("<%= pifIssueLoc.Text %>")
var ped = document.getElementById("<%= pifExpirationDate.Text %>")
if (ppn == null || pid == null || pil == null || ped == null) {
if (confirm(ppn + " " + pid + " " + pil + " " + ped)) {
confirm_value.value = "Yes";
}
else {
confirm_value.value = "No";
}
document.forms[0].appendChild(confirm_value);
}
}
</script>
这是我的asp.net代码
<tr>
<td style="padding-top: 5px;">
<asp:UpdatePanel ID="updPassport" runat="server" UpdateMode="Conditional" Visible="false" >
<ContentTemplate>
<asp:Table runat="server" ID="tblPassport" GridLines="Both" CellSpacing="0" BorderColor="Black" BorderStyle="Solid"
BorderWidth="1.5px" Font-Size="9pt">
<asp:TableHeaderRow VerticalAlign="Bottom" Height="20px">
<asp:TableHeaderCell ColumnSpan="2" CssClass="lblValueBlackFont" HorizontalAlign="Left" BackColor="#B0CCFF" >
 <asp:Label ID="lblPassportTbl_Title" Text="Passport Information" runat="server" />
</asp:TableHeaderCell>
<asp:TableHeaderCell ID="thcPassport_Sync" runat="server" ColumnSpan="2" CssClass="lblValueBlackFont" HorizontalAlign="Right" BackColor="#B0CCFF" >
<asp:Label ID="lblPassportSyncDate_Title" runat="server" Text="GIF Info Sync'd with TS: " Font-Size="8pt" Visible="False" />
<asp:Label ID="lblPassportSyncDate" runat="server" Font-Size="8pt" Visible="False" />
 <asp:Label ID="lblPassportSyncBy_Title" runat="server" Text="By: " Font-Size="8pt" Visible="False" />
<asp:Label ID="lblPassportSyncBy" runat="server" Font-Size="8pt" Visible="False" />
 
</asp:TableHeaderCell>
</asp:TableHeaderRow>
<asp:TableHeaderRow VerticalAlign="Bottom" HorizontalAlign="Center" CssClass="gv_Header" Font-Size="9pt">
<asp:TableHeaderCell runat="server" ID="thcPassport_Fields" Text=" Fields" />
<asp:TableHeaderCell runat="server" ID="thcPassport_TS" Text="Existing Data in Travel Studio" Width="350"/>
<asp:TableHeaderCell runat="server" ID="thcPassport_PIF" Text="Data Submitted on GIF" Width="420" />
<asp:TableHeaderCell runat="server" ID="thcPassport_Update" Text="Accept New Value" Width="75px" Font-Size="8pt"
ToolTip="When checked, TS data for the field will be updated with the data in the GIF column" />
</asp:TableHeaderRow>
<asp:TableRow VerticalAlign="Top" Font-Size="9pt" >
<asp:TableCell>
 
<asp:TextBox ID="rhNationality" runat="server" ReadOnly="True" Text="Nationality:" BorderStyle="Solid" BorderColor="White"
Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsNationality" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Width="75%" />
<asp:TextBox ID="tsNationalityID" runat="server" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Visible="false" />
<asp:TextBox ID="tsPassportCountryID" runat="server" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Visible="false"/>
<asp:TextBox ID="tsPassportID" runat="server" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Visible="false" />
</asp:TableCell>
<asp:TableCell VerticalAlign="Middle">
<asp:TextBox ID="pifNationality" runat="server" Text="Nationality" BorderStyle="Solid" BorderColor="White" ToolTip="Value entered is not in available list. Please choose a correct value from the dropdown." ForeColor="Red" />
<asp:DropDownList ID="ddlNationality" runat="server" AutoPostBack="True" Width="75%" />
<asp:TextBox ID="pifNationalityID" runat="server" Text="ID" BorderStyle="Solid" BorderColor="White" Visible="false" />
<asp:TextBox ID="pifNationalityCountryID" runat="server" Text="ID" BorderStyle="Solid" BorderColor="White" Visible="false" />
</asp:TableCell><asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbNationality" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow VerticalAlign="Top">
<asp:TableCell>
 
<asp:TextBox ID="rhPassportNbr" runat="server" ReadOnly="True" Text="Passport Number:" BorderStyle="Solid"
BorderColor="White" Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsPassportNbr" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Width="95%" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="pifPassportNbr" runat="server" Text="No Data Entered" BorderStyle="Solid" BorderColor="White" Width="95%" />
</asp:TableCell>
<asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbPassportNbr" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow VerticalAlign="Top">
<asp:TableCell>
 
<asp:TextBox ID="rhPassportName" runat="server" ReadOnly="True" Text="Passport Name:" BorderStyle="Solid" BorderColor="White"
Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsPassportName" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Width="95%" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="pifPassportName" runat="server" Text="No Data Entered" BorderStyle="Solid" BorderColor="White" MaxLength="60" Width="100%" />
</asp:TableCell>
<asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbPassportName" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow VerticalAlign="Top">
<asp:TableCell>
 
<asp:TextBox ID="rhIssueLoc" runat="server" ReadOnly="True" Text="Place of Issue:" BorderStyle="Solid" BorderColor="White"
Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsIssueLoc" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Width="95%" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="pifIssueLoc" runat="server" Text="No Data Entered" BorderStyle="Solid" BorderColor="White" MaxLength="50" Width="100%" />
</asp:TableCell>
<asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbIssueLoc" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow VerticalAlign="Top">
<asp:TableCell>
 
<asp:TextBox ID="rhIssueDate" runat="server" ReadOnly="True" Text="Issue Date:" BorderStyle="Solid" BorderColor="White"
Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsIssueDate" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" Width="95%" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="pifIssueDate" runat="server" Text="No Data Entered" BorderStyle="Solid" BorderColor="White" Width="95%" />
  <asp:Label ID="pifIssueDate_Err" runat="server" Text="The value entered is not a date. Please use mm/dd/yyyy format." Font-Size="7pt" CssClass="lblValueRed" Visible="False" />
</asp:TableCell>
<asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbIssueDate" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow VerticalAlign="Top">
<asp:TableCell>
 
<asp:TextBox ID="rhExpirationDate" runat="server" ReadOnly="True" Text="Expiration Date:" BorderStyle="Solid" BorderColor="White"
Font-Bold="True" Font-Size="8pt" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="tsExpirationDate" runat="server" Text="No Existing Value" ReadOnly="True" BorderStyle="Solid" BorderColor="White" />
</asp:TableCell>
<asp:TableCell>
<asp:TextBox ID="pifExpirationDate" runat="server" Text="No Data Entered" BorderStyle="Solid" BorderColor="White" />
  
<asp:Label ID="pifExpDate_Err" runat="server" Text="The value entered is not a date. Please use mm/dd/yyyy format." Font-Size="7pt" CssClass="lblValueRed" Visible="False" />
</asp:TableCell>
<asp:TableCell HorizontalAlign="Center">
<asp:CheckBox ID="ckbExpirationDate" runat="server" Checked="false" />
</asp:TableCell>
</asp:TableRow></asp:Table><table width="98%" cellpadding="20px" style="margin-top: 5px;margin-bottom: 3px" >
<tr valign="middle">
<td>
<asp:Label runat="server" ID="lblPassportUpdateMsg" Text="Unable to create or update this passenger's passport data."
CssClass="ErrorMessageRed" Width="100%" />
<asp:Label ID="lblNationality" runat="server" Text=" *Invalid Nationality " Font-Size="8pt" Visible="False" Font-Bold="True" ForeColor="Red" />
</td>
<td align="right">
<asp:Button ID="btnPassportUpdate" visible = "true" text="Update" CssClass="btnUpdate" runat="server" OnClientClick="Confirm()"/>
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
在您的javascript中，看起来您正在根据文本框值（textbox_id.Text）选择文档ID？尝试选择文本框的客户端ID属性，然后选择javascript文本值。像这样的东西：
var ppn = document.getElementById("<%= pifPassportNbr.ClientID %>").value;
var pid = document.getElementById("<%= pifIssueDate.ClientID %>").value;
var pil = document.getElementById("<%= pifIssueLoc.ClientID %>").value;
var ped = document.getElementById("<%= pifExpirationDate.ClientID %>").value;