This book is about computer programming, specifically about how to use the Google Closure Library and Google Closure Compiler. I learned things that I didn't learn from Google's own documentation for those things. Closure's a pretty nice system for writing Javascript without getting tripped up by browser incompatibilities. And this book is a pretty darned good way to learn how to use it.
There are other JS frameworks out there. They're probably pretty nice, too. I don't know much about them. Closure's been pretty good to me so far.
