jQuery 1.4 is officially out now! The jQuery team is in the process of doing a 14-days-of-jQuery-1.4 promotion, which will run through the 28th of January. This is a major release, with much of the jQuery framework being rewritten in addition to a lot of new functionality. The last major release of jQuery was in February 2009, so this has definitely been a long time coming (see my 1.4 preview post here).

There’s a new set of jQuery API documentation, with a new look and some other enhancements. One thing I’m a big fan of is the ability to see when a particular function was added to jQuery – it’s very easy to hone in on the new stuff that way. One thing I feel is still missing is the abilityto jump directly to the function implementation in the library, like how the Google Closure API documentation is setup.

Interestingly, the last day of the 14-days-of-jQuery-1.4 promotion will be the release of jQuery UI 1.8. jQuery UI 1.8 is looking to be a smaller release – a bunch of bugfixes and few somewhat underwhelming plugins, as well as support for jQuery 1.4. There are a ton of great jQuery UI widgets and enhancements that are in the proposal and development stages, but the pace of development has been very slow, which is disappointing. I’d very much like to see jQuery UI development kicked into high gear.

Overall, this is looking to be a great jQuery release. I’m impressed with the performance improvements (addClass is three times as fast now? amazing!), and the new functionality improves the experience dramatically. A lot of functionality that used to have to be gotten through plugins is now in the framework itself, which will be a boon to development. Check it out now!