[Javascript] Mimicking session state

[Rees, Mark (TWIi London)]

Hello

I have to attempt to track sessions using client-side code only. The idea is
that every time a user visits the site, they see a new picture. Thus far the
only way I can see to mimick this is to set a cookie storing the image name,
and update it if more than a set period of time (say an hour) has elapsed
since the cookie was set. 

I had hoped to use the history object but all the most useful properties
(like next and previous) are quite rightly not available in most
environments.

Does anyone have any other ideas?

Thanks in advance

Mark