Like other cookbooks in the O'Reilly library, this one is organized as a series of specific problems, with their solutions neatly presented and grouped into the major chapters. Each solution has a discussion to flesh out the details. The website has downloadable copies of the examples in the book, which I used to test out the various recipes. ECMAScript 5 is fairly new, and HTML5 is still under development, so I made sure I had the latest stable versions of the major browsers (Firefox, Google Chrome, Internet Explorer, Opera, and Safari) to see how they would cope. The HTML5 features are very sparsely supported as of yet, so those portions of the book should be considered more of a sampling of things to come rather than a definitive set of solutions.
While much of the book is applicable to today's browsers, there is a lot of coverage of the new capabilities made available in the new HTML5 specifications. Unfortunately, most browsers either do not support, or only partially support these features, so the information is only useful as a "taste of things to come".