In Greyhawk, she hates the undead. In any given GM's campaign, it could be different. However, the god of undead is Nerull. Wee Jas has a rivalry with Nerull, and so undead is a touchy issue.
One Living Greyhawk scenario had some Wee Jas followers casting spells on the dead in a graveyard to prevent them from rising as undead. (It was a "Core" module, so you may recognize it if you're an LG fan.)
http://www.furyondy.com/documents/LGDeitiesv2.0.pdf
There's more information about Wee Jas there, including the fact that the official Wee Jas has had her domain moved to be "Repose."
