Getting selected value from dropdownListBox during onClientSelect?

I would like to do implement some client-side logic in a BSP application. When the user selects a value in a dropdownListBox, I need to get the selected value.

I thought I can implement a function for the onClientSelect parameter, but this does not return the current DOM element.

How do I get at the selected value? Will this also work for other derivatives like THTMLB?

Thanks,

Martin