Getting dynamic elements' properties in C# - similar to getElementById in JS

[AGOL]

I have a page where fields are added dynamically by a JS running at the page load. So in the page I have html code like this

<TR id='TR_A1' style='display:block'>
   <TD id='A1Name' name='A1Name' >A1</TD>
   <TD> <textarea  ID='A1Value' name='A1Value' rows='6' cols='45'></textarea></TD>
</TR>

How can I access this element in c# when a button is clicked - I'm looking for something like getElementById( 'A1') in JavaScript

Thanks
Avish

[Plater]

If they are made in the javascript, they don't exist on the server side.
What you can do, is during a postback, tell the serverside about them.
(Use hidden fields, etc)

EDIT: if the TABLE itself is a server side component, it might be possible to see rows added by javascript on a postback