Hi,

I am trying to get some Java script to work on a page to show/hide a textbox control depending on the selection of a dropdown.  I have done this before but I cannot get it to work inside of my DNN code

The Javascript runs and i get into the correct path of the code but it will not reference the field and hide / show it.

Microsoft JScript runtime error: 'document.getElementsByTagName(...).style' is null or not an object

I get the above error when this line of code is run

document.getElementsByTagName('chkLeft').style.display='none';

I have tried it with style.visibility = 'visible' and style.

I have tried
var o = document.getElementsByTagName('chkLeft')[0]
o.style.display = 'none';
and it get the same error on the 2nd line

The control i am trying to reference in my page looks like this
<td align="left" class="style2">
<asp:DropDownList ID="cboRoute" runat="server" Style="z-index: 100" Font-Size="X-Small"
 Width="245px" AutoPostBack="False" Height="16px" onChange=" leftright(this.value);">
</asp:DropDownList>
<asp:CheckBox ID="chkLeft" runat="server" Text="Left" Font-Size="X-Small" Visible="False" />
<asp:CheckBox ID="chkRight" runat="server" Text="Right" Font-Size="X-Small" Visible="False" />
</td>

Any ideas would be appreciated.

Thanks for the explination. I put the code in that you suggested and now i get a different error

Error 12 Property access must assign to the property or use its value.

and the page will not even compile and run any longer, if i remove the line from the page it run again just fine ???

not sure what to make of it

document.getElementsById('<%chkLeft.ClientID%>').style.display = 'none';

this is the line i just removed

Thanks for the update, that works to get me the control name at runtime.

Now i am still back to the same first error. This is what get rendered in the [dynamic] version of the form

document.getElementsByTagName('dnn_ctr387_frmAddEditPatDrugMaster_pnlLeftRight').style.display = 'inline';

I have tried to set the style.display of the checkbox and now have also tried with a simple panel and still get the same original error.

Microsoft JScript runtime error: 'document.getElementsByTagName(...).style' is null or not an object

Thanks for any additional help.