In this chapter, we've built a second practical application and talked a lot about how a design can change as an application develops. While we produce an initial application architecture with the best of intentions and the knowledge we have hand as the application develops, it's important to be flexible in order to produce a successful final product. We also introduced routing, more on data binding, and showed how code can be reused in a variety of ways.

In the next chapter, we'll build an application that will be familiar to most readers: an e-mail client. It'll be a responsive app tailored for both desktop and tablet, and we'll once again take the ideas we've already discussed and develop them even further.