Okay, a short blog post like this (or even a big one, like those penned by Steve Yegge) can't tell you everything *known today* about Ajax, forget "all you ever need to know". In fact, it can't tell you everything about anything worth knowing. There is just way too much information and knowledge around us about almost everything, consequential or not. To make things worse, at least for those who claim to "tell everything", this body of information and knowledge keeps growing every minue.
So why did I choose this particular title? No, I didn't intend to write everything I know about Ajax. It is just a link-bait. Seems to have worked quite well for others. Might work for me as well.
What I really want to do in this post is to write a short review of "Ajax -- The Definitive Guide", a book published by O'Reilly. Those who are familiar with Oreilly's The Definitive Guide series know that these books have a reputation of being very comprehensive and all encompassing about the chosen topic. This certainly seems to be the case for a number of books in this series on my bookshelf, such as "JavaScript: The Definitive Guide" and "SSH, The Secure Shell: The Definitive Guide". But a definitive guide on something like Ajax? It would have to cover a lot of stuff, in all their fullness and fine details, to do justice to the title: the basics of Ajax interactions, (X)HTML, JavaScript, XML, XmlHttpRequest, CSS, DOM, browser idiosyncrasies, Ajax programming style and design patterns, tips-n-tricks, numerous browser side Ajax libraries such as prototype, YUI library, jQuery etc. and their integration with server side frameworks such as RoR, Drupal etc. The list is fairly long, if not endless. And each topic worthy of a book by itself.
On the other hand, the book does provide good introduction to basic concepts, is quite readable, includes a lot of source code for non-trivial working programs and lists relevant resources, such as Ajax libraries, frameworks and applications, in its References section. I especially liked the "chat" and "whiteboard" application that allows two or more users to share a whiteboard and chat through their browsers.
Okay, so how does this book compares with other books on the same topic? This is a tough question, for I haven't been paying attention to most books that have come out on this topic. Though there is a answer, and it comes from this Amazon Sales Rank comparison chart:
A higher Sales Rank for an item implies that more people are buying it from Amazon. This doesn't tell how well a particular book will meet your needs but just that the high ranking items, in general, are being bought by more people than the low ranking ones. The above chart does indicate that Ajax -- The Definitive Guide is outselling its rivals, at least at the time of this review (March 17-18, 2008).