site validation (up/down)

I have been poking around the JavaScript sites to no avail -
and looking over an O'Reilly JavaScript book to no avail also -

So here is my question to the masters -

Main web site is "FrontPage" static stuff being hosted by our ISP, you click
a link
to get to the customer web site; which is entirely hosted on our AS/400 -
Here is our dilemma (please, I would rather not, but its not my call)
we IPL and do a restrictive backup each week on Friday nights,
is there "any" JavaScript that can check to see first if the referenced http
site is
up or down before I forward the request off ; that way I could send an alert
box
to the surfer to let them know that the site is down for "maintenance"

I thought about "updating" the outside web hosted pages, but that could get
really messy, as I would
have 11 pages to "fix" to say down, and then turn back when we are live; not
to mention the things
I would have to do since that site is done entirely in FrontPage2000 in
order to keep things in sync;
and when I get hit by a truck, someone after me will forget about it and
screw things all up.

Thanks for any direction in utilizing JavaScript (or if I HAVE to I will
just let them get the error of site not found)
This also plays into an attempt at sending an alert message to users that
are on-line near the time we are
going into a restrictive state for the backup and IPL... Yuk..


Mark A. Manske
Fleming CSD - Plymouth Division
Sr. Project Lead
http://www.minter-weisman.com
mailto:mmanske@minter-weisman.com