Debugging Node.js can be very difficult. Most times when something goes wrong it would take a while to get to the root of the problem because the error message may not be descriptive enough or
there’s a variable that you expect to have a value but it’s
The first thing that comes to mind when debugging in Node.js is usually to use
console.log. This usually will get you a solution but in the long run, it wastes time.
We’ve all been in a situation where we had to use
console.log multiple times because once was not enough. In a bid to quickly solve the problem we spend more time logging at different
points of the application.
But it does not have to be that way. There’s a much simpler and more effective way of debugging in Node.js. It’s by using a very simple keyword:
In Node.js it’s a little different, you have to do more than just typing the keyword. To enable debugging in Node.js, in addition to adding
debugger; in your code, you have to run the application using:
node inspect <file_name.js>
There are other ways to debug Node.js aside from
node-inspect, some are:
- Chrome DevTools: I’d expand more on this later in the article.
- Visual Studio Code: It’s the most effective if you already use VS Code.
- Visual Studio
- Some JetBrains IDEs
- Eclipse IDE
Debugging with Chrome DevTools
We’ll be using AdonisJs (a Node.js web framework) as an example. To enable debugging mode on Adonis run:
adonis serve --dev --debug
This debugger makes use of Chrome DevTools so head over to Chrome (If you have it installed). You should see the Node.js icon when you enable the DevTools. Clicking it will open a new window for debugging.
Whenever the execution of your application encounters the keyword
debugger, it’ll automatically pause execution and open the Chrome debugger window. You can do a lot of things in this window:
- See the value of scope and global variables
- View the call stack: allows you to see all the functions that were executed up until the current function being executed
- Resume execution
- Step over to the next function call
- Step into the next function call
- Step out of the current function
- Pause execution where exceptions are thrown
- and many more
Voila! That’s it. With this, you can easily debug your AdonisJs application and not have to
You can check Node.js docs for more information on debuggers.