asp.net textbox doesn't have clientmode attribute

If I declare a DIV and set it to runat server I get a clientmode attribute which I can set to determine what th开发者_Go百科e ID comes out to be on the rendered page. I need to do this for a drop down and a textbox but clientmode isn't available on those controls.

What can I do? I don't want to do some crazy workaround. If it comes to it i'll just do an auto postback and do what I need there.

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DropDownLists and TextBoxes have a ClientID attribute that tells you the client-side ids of the rendered HTML elements.