davidflanagan.com > August 2006

In Part I, Core JavaScript, the chapter on functions (Chapter 8) has been expanded, with particular emphasis on nested functions and closures. The material on defining your own classes has also been expanded and moved to a chapter of its own (Chapter 9). Chapter 10 is another new chapter that covers namespaces, which are essential for writing modular, reusable code. Finally, Chapter 12 demonstrates how to use JavaScript to actually script Java; it shows how to embed a JavaScript interpreter within a Java 6 application and how to use JavaScript to create Java objects and invoke methods on those objects.

In Part II, Client-Side JavaScript, the coverage of the legacy (Level 0) Document Object Model has been merged with the coverage of the W3C standard DOM. Because the DOM is now universally implemented, there is no need for two separate chapters on manipulating documents. The biggest change in Part II, however, is the amount of new material:

• Chapter 19, Cookies and Client-Side Persistence, has updated coverage of cookies and new coverage of other client-side persistence techniques.
• Chapter 20, Scripting HTTP, explains how to make scripted HTTP requests using the powerful XMLHttpRequest object, which is the enabling technology for Ajax-style web applications.
• Chapter 21, JavaScript and XML, demonstrates how to use JavaScript to create, load, parse, transform, query, serialize, and extract information from XML documents. It also introduces the E4X extension to the core JavaScript language.
• Chapter 22, Scripted Client-Side Graphics, explains JavaScript's graphics capabilities. It covers simple image rollovers and animations but also explains advanced scripted graphics using the cutting-edge <canvas> tag. It also demonstrates other ways to create dynamic, scripted client-side graphics using SVG, VML, the Flash plug-in, and the Java plug-in.
• Chapter 23, Scripting Java Applets and Flash Movies, has added coverage of the Flash plug-in to its coverage of the Java plug-in. It now explains how to script Flash movies as well as Java applets.

Part III, the reference section for the core JavaScript API, is little changed from the previous edition, because that API has remained stable. If you have used the fourth edition, you'll find this part of the book comfortingly familiar.

The big change to the reference material is that the documentation of the DOM API, which was previously segregated into a section of its own, has been fully integrated into Part IV, the client-side JavaScript reference section. Now there is only one client-side reference section to consult. No more looking up the Document object in one reference section and then looking up the HTMLDocument object in the other. Reference material for DOM interfaces that were never (widely) implemented in web browsers has simply been cut. The NodeIterator interface, for example, is simply not available in web browsers, and it no longer clutters up this book. The focus has also been moved away from the awkwardly formal interfaces defined by the DOM specification and onto the JavaScript objects that actually implement those interfaces. So, for example, getComputedStyle() is now documented as a method of the Window object, where you d expect it, rather than as a method of the AbstractView interface. There is no reason that client-side JavaScript programmers should care about AbstractView, and it has simply been removed from the reference. All these changes result in a simpler, easier-to-use client-side reference section.