Javascript Timezone Check

[sunder]

Hi all,
I am in the challenging effort to put together a time zone check for users using a global application originally written in PHP.
Sadly, it seems I struck at a point to I am trying to gather some help in these forums.
Problem is the following:
the server saves time zone information in the user profile, and it will keep a value of the difference between the Users time and the Server time.
Assuming the Server is GMT+1 and the user is GMT-7, the diff will be -8 hours.
On the other hand, if the server is GMT+1 and the user is GMT+6, the stored diff will be 5 hours.
Now to avoid typos and user problems, I want to run a small script at login that compares the user's PC time to the databases assumed time.
The problem I face: I use UNIX timestamps to store values.
I tried every single Java code I knew and also what I could find, but as soon as I want to convert the USER-SIDE date to a timestamp it will return the SERVER's time as a timestamp e.g. parse();
So:
// Get the user's time from his or her PC
d = new Date( );

If I use d.getFullYear(), d.getDate() etc. this will accurately return the user's time, e.g.
2008-Jan-25 15:20
But if I use this info and try to parse() the string, the timestamp returned will actually be the Server's time!
So, anyone has any good ideas how to solve this timezone-check riddle?
Thanks in advance.

[CloudedVision]

i would use PHP or some other server side language to do this. there's no need for javascript.

[sunder]

Thanks for the prompt answer CloudedVision.

Actually, I am already utilizing PHP to get the server side time and also, the REQUIRED time for the user based on the saved time difference data.

However, I can not use server side to determine what is the time on the user's PC, and actually this script would need to check if the server side data is accurate.

The challenge here: I could make a comparison of JAVA user time string and PHP server side string to see if it matches even without converting the user side time to a unix timestamp, BUT, here is an example where this fails:

user time string: 2008-Apr-12 14:59
server required string: 2008-Apr-12 15:01

I wanted a 3 minutes threshold that is acceptable as the difference between server side and user side, but in this case I can not calculate it without using timestamps since not even the hours match.

I could make EXCEPTIONS but that would take lots and lots of rows and resources.

That is why I asked this question if anyone knows a better solution for this trouble.