In this chapter, we have explored a variety of real-world challenges—topics that any JavaScript programmer may find themselves exposed to both within the browser and on the server. Writing clean code in JavaScript is not only about the language itself but about the web ecosystem that it exists within and the demands that this brings. Through our explorations of the DOM, routing, dependency management, and security, we have hopefully gained an insight into the technicalities of the problem domains that JavaScript often deals with, and an appreciation for the many frameworks, libraries, and standards-driven APIs that exist to help us to deal with these problems.

In the next chapter, we'll delve into the art of writing clean tests, a vitally important task, not only because it gives us confidence in our own code, but because it ensures the kind of reliability that users rightfully expect from our software.