JavaScript Patterns

Chapter 2. Essentials

This chapter discusses essential best practices, patterns, and habits for writing high-quality JavaScript code, such as avoiding globals, using single var declarations, pre-caching length in loops, following coding conventions, and more. The chapter also includes some habits not necessarily related to the code itself, but more about the overall code creation process, including writing API documentation, conducting peer reviews, and running JSLint. These habits and best practices can help you write better, more understandable, and maintainable code—code to be proud of (and be able to figure out) when revisiting it months and years down the road.

Writing Maintainable Code

Software bugs are costly to fix. And their cost increases over time, especially if the bugs creep into the publicly released product. It’s best if you can fix a bug right away, as soon you find it; this is when the problem your code solves is still fresh in your head. Otherwise you move on to other tasks and forget all about that particular code. Revisiting the code after some time has passed requires:

• Time to relearn and understand the problem

• Time to understand the code that is supposed to solve the problem

Another problem, specific to bigger projects or companies, is that the person who eventually fixes the bug is not the same person who created the bug (and also not the same person who found the bug). It’s therefore critical to reduce the time it takes to understand code, either written ...