how do i disable the property title="....."?

i have made a button onmouseover displays a <div> containing some help text.

i want to make this as compatible as possible, so if the user does not have javascript, i want the tooltip to show (by means of title="help text...")

but if he has javascript on, the help <div> and the tooltip will show, so using javascript, how can i disable the
title="help text..."?