One of the most crucial parts of the development process of any program, Software, Or application is debugging. And it has a very significant impact on the performance of the features and functionalities of the software and program. 

Not just in NodeJS but in every development process the developers have to identify and resolve issues that might make the software or program slow or damaged. 

The most common challenges while making NodeJS applications are identifying performance bottlenecks, Memory leaks and Asynchronous operations. While callback functions and promises are also tricky. 

For an efficient debugging process the developers might have to use third-party tools, Chrome devtools and NodeJS debugger. And by having a good experience with these developers can make their whole development process smoother and easier. As, good debugging can not only resolve the present issues but also helps in saving the program or software in future issues. 

So, to debug like a pro let’s just start with the fundamentals. 

Fundamentals of NodeJS debugging

1. Watchers: 

Watchers help you monitor specific expressions and variables and see their real time value changing and analysing their performance. 

2. Breakpoints: 

Breakpoints are the markers or points where the process of execution will be paused and will let you inspect the current state of your program or application. 

NodeJS debugging tools:

1. Chrome DevTools:

 You can integrate Chrome devtools with your nodeJs application by entering the code “node -inspect <my_app.js>”. After integrating chrome devtools you’ll be able to watch variables set breakpoints and view the call stack etc. 

2. NodeJS debugger: 

It is a built-in debugger that you can start running by entering the command

node inspect <my_app.js>

Setting up an NodeJS debugging environment

To set up a debugging environment you have to choose an IDE, The most popular and efficient names are webstorm and VS code. 

A complete guide to set up a debugging environment:

1) The first step is to install NodeJS, You can download NodeJS latest version and as per your device and Operating system from the official website of nodeJS. 

2) Selecting an IDE is the second option, Which I mentioned above the two most popular and most used names you can download, Which are webstorm and VS code.

3) The third step is to install extensions and plugins. If you’ve chosen VS code as the IDE then you have to download the extensions named “NodeJS debugger”, That provides quite a range of different robust features to help you debug better and quicker. 

And if you choose Webstorm as the IDE then it has an inbuilt NodeJS debugging feature. But you have to make sure the NodeJS plugin is enabled in the settings. 

Setting up NodeJS debugging Configuration:

1. In the VS  code you have to create a file named “launch.json” into the “.vscode” folder. And then configure it according to which you need your application to be launched for debugging. 

1. In the Webstorm, you can set up and configure your debug/run just by going to the run menu and choosing “Edit configurations”.

The Usage of NodeJS Debugger

Starting Process:

Firstly, you should open your terminal. Secondly, To run your application in Node Js Debugging mode by entering the command node inspect <my_app.js>. And this launches your application in debugging mode. 

Some basic commands to run and their functionalities:

Next or n, Step or s, Cont or c, Set Breakpoint or sb ( To set a breakpoint ), List or l, watch(“name of variable”). 

All these commands are really helpful for the developer to locate and resolve the existing bugs and make the application or software error-free. 

NodeJS debugging with ChromeDev Tools:

 Chrome dev tools help Node Js applications to easily identify and resolve bugs due to its vast debugging features. 

Launching Chrome Dev tools:

Firstly run your node.js app with node inspect <my_app.js>. Secondly, Open google chrome and  then go to “chrome://inspect”. The third step of chrome dev tools is to click on “Open dedicated Devtool for node”. Lastly your app will appear within “Remote target” And then to start debugging you have to click on “inspect”.

Usage of Console logging:

A command “console.log()” is used to print variables, And function outputs in chrome devtools. But you should comment on all the console related lines. So, that your log will be clean during the production period. 

Different type of Console Methods:

•  Console.error() command makes the error red in the output and makes it easy to spot the error.
• Console.warn() indicates the potential issues with yellow colour indicating the warnings in the code.
• Console.log() is the command that is used to get informational messages in output.
• Console.debug() shows a log related to debugging which is perfect for the debugging process in development. 

Watchers and Breakpoints handling

Setting up and managing Breakpoints in Node.js:

Like I mentioned above, a breakpoint is a point of code where the execution pauses, So, that you can determine the state and performance of your code and program. 

Usage of Watchers can help you to keep an eye on specific variables:

The watchers help you monitor some specific variables and the changes that are being made in it. 

 Some Techniques for Conditional breakpoints:

The conditional breakpoints means that when a certain condition will meet in the code then the code will stop at the breakpoint. This helps developers analyse the type of error and issue that you are facing in your development process and then make strategies accordingly. 

Go to chrome devtools, Right click on the breakpoint you want to add condition and then click on “Edit Breakpoint” And then add the condition that you want. 

Detection of Memory leak and Performance Profiling

Techniques and Tools to detect memory leaks:

When unused memory isn’t released it causes memory leak. Tools like heapdump and the Node Js built-in inspector helps identify memory leaks and you can easily capture screenshots to analyse the piece of code or objects that are present and shouldn’t be there. 

The Profiling tools of NodeJs:

If you run your NodeJs application with ” node -inspect” then it will open profiling tools. And the chrome devtools will open. Where you can see the performance of CPU, Memory and other aspects to identify the issues in the code and then make strategies accordingly. 

Debugging of Asynchronous code

Challenges in Asynchronous debugging:

The debugging of Asynchronous code is full of challenges. Because in this the code doesn’t flow in sequence. And the callbacks, Functions, Async/Await, and Promises makes it a bit more complex to track down the issues.

Tips and Techniques To identify issues in Asynchronous Code:

Tools like LongJohn can definitely help you a lot in tracking down the progress and performances. Secondly, another best tip is to use logs as much as you can to know the flow of the code and to make it easier for you to analyse the issues and make strategies to find the best possible solutions about it. 

Using Third-Party Debugging tools:

A long list of third-party debugging tools that you can use to identify the issues in the performance, Features and memory. 

Nodemon, Noden, PM2, has both pros and cons of using. Like its pros, it helps in better error-tracking. However its con is that you should learn about them and set them with the application that will make the application bigger. 

Conclusion:

Firstly, to debug NodeJS like a pro you should have a better understanding of the different methods that you can use like Chrome Dev tools, Debugging for Asynchronous code, And watchers and breakpoints handling. Secondly, there are many techniques to identify and track the issues in the code. Lastly, After analysing the errors the developers take steps accordingly and make the application or program bug-free.