Chapter 3. Ajax Patterns

Design patterns describe programming techniques to solve common problems. Given that programming has been around for several decades, chances are that many of the problems you face every day have already been solved by someone else. Since the mid-1990s, a lot of attention has been drawn to design patterns as a way to cut development time.

Even though the term Ajax has been around only since early 2005, the techniques that Ajax describes have been used since the late 1990s, giving rise to several Ajax patterns that solve specific problems. You've already seen some of these patterns in action, namely the hidden frame technique and asynchronous XHR calls. These are communication patterns between the client and server using JavaScript. As you may have expected, there are many more types of patterns.

Author and programmer Michael Mahemoff was the first to attempt to document Ajax design patterns at his web site, www.ajaxpatterns.org. The patterns presented in this chapter are a mixture of Mahemoff's and others that your authors have identified. Note that design patterns, whether described on a web site or in a book, can never be official, only accepted. Design patterns are not standards to be followed, but merely designs of solutions that have worked previously. It is up to the development community to generate a "collective wisdom" around specific patterns; it's up to the individual developer to decide whether to implement a given pattern in his or her own application.