Web Development with Node and Express

Chapter 20. Debugging

“Debugging” is perhaps an unfortunate term, what with its association with defects. The fact is, what we refer to as “debugging” is an activity you will find yourself doing all the time, whether you’re implementing a new feature, learning how something works, or actually fixing a bug. A better term might be “exploring,” but we’ll stick with “debugging,” since the activity it refers to is unambiguous, regardless of the motivation.

Debugging is an oft-neglected skill: it seems to be that most programmers are expected to be born knowing how to do it. Perhaps computer science professors and book authors see debugging as such an obvious skill that they overlook it.

The fact is, debugging is a skill that can be taught, and it is an important way by which programmers come to understand not just the framework they are working in, but also their own code and that of their team.

In this chapter, we’ll discuss some of the tools and techniques you can use for debugging Node and Express applications effectively.

The First Principle of Debugging

As the name implies, “debugging” often refers to the process of finding and eliminating defects. Before we talk about tools, let’s consider some general debugging principles.

How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?

— Sir Authur Conan Doyle

The first and most important principle of debugging is the process of elimination. Modern computer systems ...