JavaScript: The Definitive Guide, 6th Edition

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JavaScript The Definitive Guide, 6th Edition

Released during the early days of the Web, in 1995, JavaScript has come a long way: Initially a client-side scripting language typically (mis)used for decorative effects, it is now an essential part of countless major websites. Its increasing capabilities and popularity are due to several factors, including the development of libraries that resolve earlier stumbling blocks that held the language back (such as inconsistencies among the implementations in different vendors' browsers). JavaScript: The Definitive Guide, authored by David Flanagan, was first published just one year later, in 1996, with several significant updates made since then.

The book is now in its sixth edition, under the ISBN 978-0596805524, and was published on 10 May 2011 by O'Reilly Media (who kindly provided me with a review copy). At 1100 pages, it certainly feels heavier than its advertised 2.6 pounds — but that may only be a side effect of the thought of wading through over a thousand pages of technical explanations and example code. Yet one could argue that the size is justified, considering the amount of information the book conveys, and its obvious aim to be a comprehensive treatment of the language. The material is organized into four parts, including 22 chapters. On the publisher's Web page, visitors will find a brief description, the complete table of contents, a few consumer reviews, reported errata (seven as of this writing, and none confirmed), the example code used in the book, some free content (the first chapter), and links to purchase the print and e-book versions.

The book commences with a multipart introduction, which begins with the sentence "JavaScript is the programming language of the Web." Even though that statement is not true — since there are many other Web programming languages — it does hint at the importance of the language in the mind of the author, and his willingness to put so much effort into creating such a detailed monograph. The introduction is also the first point in the book where one sees the clear demarcation made by the author between core JavaScript (i.e., the language definition, regardless of its runtime environment) and client-side JavaScript (i.e., usage of the language within Web browsers, including the use of libraries). Both areas are covered in great detail in the first two parts of the book, in quasi-tutorial format, while the last two parts cover the same areas, but in a purely reference format.

Specifically, the first part of the book, "Core JavaScript", offers almost a dozen chapters that explicate the basics of the language: its lexical structure; types, values, and variables; expressions and operators; statements; objects; arrays; functions; classes and modules; regular expressions; JavaScript subsets and extensions; and server-side JavaScript. At almost 300 pages, this part alone could form its own volume. The manner in which the author dives into the technical details, and the amount of example code, immediately make it evident that the book is intended for readers who have experience programming, although not necessarily in JavaScript. In fact, some readers — especially newbie programmers — may become frustrated with those places in the narrative where the explanation is not entirely clear. For instance, on page 7, the "points array from above" refers not to any code on that page, but instead refers to an array defined two pages earlier. Fortunately, such stumbling blocks are infrequent. For experienced JavaScript programmers, these chapters could provide a comprehensive review. For readers new to JavaScript, the material may seem overly dry, but the illustrative code should be quite helpful.

The ten chapters that compose the second part of the book, "Client-Side JavaScript", show how to work with the language within a Web browser. This includes learning how to embed JavaScript code in HTML files; differences among browsers and the versions thereof; the security of JavaScript code; the Window object; how to access and manage the elements within the Document Object Model (DOM); scripting CSS styles; events, and methods of handling them; scripting HTTP, and its use in Ajax (reflected in this edition's subtitle, "Activate Your Web Pages"); the jQuery library; techniques for storing data on the user's computer; how to use JavaScript to dynamically create and manipulate graphics, audio, and video content, as well as charts and drawings; and, lastly, the use of several HTML5 APIs. Speaking of that last topic, probably the most significant changes in this edition, versus the previous one, is the coverage of ECMAScript 5, as well as the new objects and methods introduced with HTML5. Naturally, some of these enhancements do not work in any version of Internet Explorer but the most recent, so the author discusses workarounds, if available.

As noted earlier, the third and fourth parts of the book constitute the purely reference material, with the first part focusing on core JavaScript, and the latter on the client-side aspects of the language. Every chapter is organized into a series of entries, each devoted to a particular class or object, ordered alphabetically. For each entry, the reader is given a brief synopsis, description, and in some cases example code and references to other entries. Each class entry also includes information on its properties and methods, where applicable. Each single method entry includes information on its arguments and any return value. The book concludes with what is arguably the longest and possibly most valuable index I have ever seen in a computer book.

There are only a few immediately-evident weaknesses of this book: Firstly, there are some phrases that may be clear to the author, but likely will prove baffling to the typical reader — e.g., "nonlinear cross-reference problem" (page 8) and "the jQuery gives a synopsis of each method" (page 523). Secondly, some of the example HTML code could have been written better, such as the use of an HTML table for defining the layout of a simple form, with labels and fields (page 13). Finally, despite the claims of the marketing copy that this title is suitable as both "an example-driven programmer's guide or a complete desk reference", it would serve better as the latter, and not as a tutorial for learning the language. Clearly, the more comfortable one feels with computer programming — especially JavaScript itself — the more that one could get out of this book.

On the other hand, there are far more pluses than minuses. One of the real strengths of the book is how the author does not hesitate to use (sometimes lengthy) blocks of code, with explanatory comments for almost every line, to clarify the language — as opposed to paragraphs of text, which could have easily doubled the length of the first two parts (which comprise roughly the first two thirds of the book). Also, in conjunction with the narrative and code fragments, the author makes effective use of figures whenever needed — particularly in Chapter 21, in demonstrating how to work with graphics and multimedia content.

Evolving with the language itself, and again brought up to date, JavaScript: The Definitive Guide still retains its crown as the ultimate reference resource for JavaScript programmers.

Copyright © 2011 Michael J. Ross. All rights reserved.
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