The standard ecmascript regex isn’t ready for unicode (see http://blog.stevenlevithan.com/archives/javascript-regex-and-unicode).
So you have to use an external regex library. I used this one (with the unicode plugin) in the past : http://xregexp.com/
In your case, you may have to escape the char é
as \u00E9
and defining a range englobing e, é, ê, etc.
EDIT : I just saw the comment of Alex : you’ll find inside the range for the accented equivalent of e.