The "Web based language" haXe focuses on targeting a variety of web platforms directly with a single syntax. However, haXe is not just a framework like Ruby on Rails. Instead, it targets virtual machines at the bytecode level where possible. With a single class file, it is possible to produce javascript, php, SWF objects, etc.

What is even more impressive is that haXe is able to provide these targets with expressive type checking capabilities, enabling better debugging facilities, while also improving execution efficiency in many cases.

The authors do a great job of introducing the specifics of the language, and help the reader wrap their head around the kind of inter-platform functionality that haXe makes possible.

The only negative for this book is the fact that it is slightly outdated, given that it was written for haXe 1.15, while haXe itself has recently hit version 2.0. However, if you're looking for a comprehensive introduction to what haXe is all about, I would still recommend buying this book, and also subscribing to the haXe mailing list to stay on top of all the new features the language is offering.