This chapter introduced us to the concept of component composition. Components are the building blocks of a scalable JavaScript application. The common components we're likely to encounter include things like modules, models/collections, controllers/views, and templates. While these patterns help us achieve a level of consistency, they're not enough on their own to make our code work well under various scaling influencers. This is why we need to extend these components, providing our own generic implementations that specific features of our application can further extend and use.

Depending on the various scaling factors our application encounters, different approaches may be taken in getting generic functionality into our components. One approach is to keep extending the component hierarchy, and keep everything encapsulated and hidden away from the outside world. Another approach is to plug logic and properties into components when they're created. The cost is more complexity for...