Design patterns
The second part of this chapter presents a JavaScript approach to a subset of the design patterns introduced by the book called Design Patterns: Elements of Reusable Object-Oriented Software, an influential book most commonly referred to as the Book of Four or the Gang of Four, or GoF (after its four authors). The patterns discussed in the GoF book are divided into three groups:
Creational patterns that deal with how objects are created (instantiated)
Structural patterns that describe how different objects can be composed in order to provide new functionality
Behavioral patterns that describe ways for objects to communicate with each other
There are 23 patterns in the Book of Four and more patterns have been identified since the book's publication. It's way beyond the scope of this book to discuss all of them, so the remainder of the chapter demonstrates only four, along with examples of their implementation in JavaScript. Remember that the patterns are more about interfaces...
