Not a book for beginners, though it does cover Javascript basics enough for most programmers in other languages. Modern, thorough, well thought through and dealing with practical problems - not those of image rollovers and noddy stuff, but deeper things, such as dealing with cross browser differences in event handling, etc.. Goes into depth on the DOM and XML, coding styles and the 'inheritance' model of Javascript. In short, the kinds of things professionals trying to build 'Googlesque' user interfaces will need. It's not a reference manual, and it's not really a 'cook book', it's something in between, and it is the best technical read I've come across for a while! I've learnt a lot - not least that Javascript is a lot more now than it was...