Need to make a textbox required if radio button is selected

[mcooley]

Hello all. New user (and new to javascript) looking for some guidance.

I have a form with a radio button list that contains 4 selections (A,B,C and "Other"). The "Other" option has a textbox next to it that I want to make required if the "Other" option is selected from the list.

Any help would be greatly appreciated.

Thanks,
Mike