HTML 5 adds a "classList" property to HTMLElement. The classList property makes it easy to add, remove, and toggle classes on an Element. We should implement support for this in WebKit!
See <http://www.whatwg.org/specs/web-apps/current-work/multipage/dom.html#dom-classlist> for a little bit of information about classList, and <http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#domtokenlist-0> for information about the DOMTokenList interface, which is the interface the object returned by classList implements.
I sent an email to the WHATWG mailing list asking about the case-sensitivity of element.classList methods: <http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2009-June/020425.html>.
*** This bug has been marked as a duplicate of 20709 ***