If you're ready to use Closure to build rich web applications with JavaScript, this hands-on guide has precisely what you need to learn this suite of tools in depth. Closure makes it easy for experienced JavaScript developers to write and maintain large and complex codebases―as Google has demonstrated by using Closure with Gmail, Google Docs, and Google Maps. Author and Closure contributor Michael Bolin has included numerous code examples and best practices, as well as valuable information not available publicly until now. You'll learn all about Closure's Library, Compiler, Templates, testing framework, and Inspector―including how to minify JavaScript code with the Compiler, and why the combination of the Compiler and the Library is what sets Closure apart from other JavaScript toolkits.
An absolute must for everyone working with Closure on real-world projects. There are no other books on Closure anyways and this one is indeed not bad and comprehensive. It covers "the whole package" of library, compiler ... and how it all works together.
The main problem I have with this book is that it is partly written as a reference (e.g. lots of pages covering library functions one after the other) and partly as a tutorial (e.g. about ui components). Of course this makes it imperfect in both. If you want to find out a specific detail about ui component, you might have to search for it in pages of running text. If on the other hand you want to know what a specific library function does you will find 4 references in the index.
Another problem (but all books have that) is that Closure frequently changes so some specific detail could be inaccurate.
Use this book in conjunction with the excellent (but piece-meal) online documentation and you have everything on your hands to make working with Closure a success.
Before reading this book, I hacked around on Google Closure and got some results from exploring their web site. This book really filled in a lot of the gaps in information that was missing from the API specs such as how to implement a login dialog. I would not have been able to implement version 2 of this beta had it not been for this book.