怎么获取gridview<FooterTemplate>中控件的ID

C# code

<asp:TemplateField HeaderText="单位">                  <EditItemTemplate>                   <asp:TextBox runat="server" ID="EditUnit" Text='<%# Bind("iunit") %>' Width="200px"/>                   </EditItemTemplate>                  <ItemTemplate>                      <asp:Label ID="lbIunit" runat="server" Text='<%# Bind("iunit") %>'></asp:Label>                  </ItemTemplate>                  <FooterTemplate>                      <asp:TextBox ID="txtUnit" runat="server" Width="200px" Onclick="chose()"></asp:TextBox>                  </FooterTemplate></asp:TemplateField>

怎么在前台获取TextBox的ID?

[解决办法]
或者
t = document.getElementById("<%=GridView1.ClientID%>").rows[document.getElementById("<%=GridView1.ClientID%>").rows.length - 1].getElementsByTagName("input")[0];
alert(t.value)