The demo (just above the comments) in the jQuery docs is helpful.

http://api.jquery.com/mouseenter/

Ben Nadel's blog is worth a daily read. Probably half of his content these days is about JavaScript. Ben and his partner just raised $1.5 million for their Invision app that lets you build interactive prototypes using PhotoShop.

http://techcrunch.com/2012/02/22/invision-raises-1-5m-for-be...

jquery has been around for a while and so has this post. but nonetheless a good reminder what a pain js would be without it.

a real confusing point for quite of us developers.