Chapter 4. Design Patterns

A design pattern is a reusable solution to a recurring problem; the term is really broad in its definition and can span multiple domains of application. However, the term is often associated with a well-known set of object-oriented patterns that were popularized in the 90's by the book, Design Patterns: Elements of Reusable Object-Oriented Software, Pearson Education by the almost legendary Gang of Four (GoF): Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. We will often refer to these specific set of patterns as traditional design patterns, or GoF design patterns.

Applying this set of object-oriented design patterns in JavaScript is not as linear and formal as it would happen in a class-based object-oriented language. As we know, JavaScript is multi-paradigm, object-oriented, and prototype-based, and has dynamic typing; it treats functions as first class citizens, and allows functional programming styles. These characteristics make JavaScript a very...