How should unhandled errors preferably be resolved in Node.js ?

Node.js is a popular platform that lets developers make web apps that are scalable and work well. But, just like with any other programming language, mistakes can happen during the development process. These mistakes can cause the program to behave in unexpected ways or even crash. Unhandled errors, in particular, can be very troublesome because they can make your Node.js app crash or give you results you didn’t expect. In this article, we’ll talk about the best way to fix unhandled errors in Node.js.

What are “Errors Not Handled” or “Unhandled Errors”?

Errors that happen during runtime and are not caught by an error handler are called “unhandled errors.” These errors can make your Node.js app crash or give you results you didn’t expect. Unhandled errors can happen in a typical Node.js app for a number of reasons, such as wrong data, network failures, programming errors, or system failures. Uncaught exceptions and unhandled rejections are two examples of unhandled errors.

Errors that are not caught by a try-catch block or an error handler are called “uncaught exceptions.” On the other hand, unhandled rejections are errors in promises that are not taken care of by a catch() block. Both kinds of errors can cause your Node.js app to crash, which makes it hard to find out what’s wrong and fix it.

Why is it important to fix errors that haven’t been fixed?

Errors that aren’t handled can cause the application to crash, which causes downtime and a bad experience for users. They can also leave the application in a state that isn’t consistent, which makes it hard to find problems and fix them. Proper error handling makes sure that errors are caught and dealt with in the right way. This keeps the app from crashing and makes the user’s experience better.

Resolving Unhandled Errors: To fix Node.js errors that aren’t being handled, you need to add error handling to your application. Most of the time, try-catch blocks, error handlers, and promise rejections are used in Node.js to handle errors. By putting in place ways to handle errors, you can catch and fix them before they cause your application to crash or do something else unexpected.

1. Blocks with Try-catch Statements: Try-catch blocks are used to catch errors that happen at the same time as the program is running. The code that could throw an error is wrapped in a try-catch block. If there is an error, the catch block is run, and the error is caught and dealt with. Here’s what a try-catch block looks like:  

Javascript

try {
    // Code that can potentially throw an error
} catch (error) {
    // Error handling code
}

Note: However, be careful now, not to use try-catch in asynchronous code, as the error thrown by the async code will no longer be caught in the program.

Below is an example to show what happens when we use try-catch in async programming.

Javascript

try {
    setTimeout(function () {
        var err = new Error("Hello");

        throw err;
    }, 1000);
} catch (err) {
    // Example error won't be caught
    // here... crashing our application
    // hence the need for domains
}

2. Error Handlers: Error handlers are used to catch errors that happen at different times during the runtime. In Node.js, you can make an error handler by implementing a middleware function that takes four arguments: err, req, res, and next. The error object is in the err argument, and the next argument is a function that passes control to the next middleware function. Here’s what an error handler looks like:

Javascript

app.use((err, req, res, next) => {
    console.error(err.stack);
    res.status(500).send('Something broke!');
});

3. Promise Rejections: Errors in the promises may be found and corrected with the help of promise rejections. A call is made to the catch() function if a promise is broken; this allows any errors to be captured and dealt with appropriately. The following is an example of a broken promise:

Javascript

fetch('https://...com/data')
    .then(response => {
        // Process the response
    })
    .catch(error => {
        // Handle the error
    });

The Most Effective Methods for Addressing Errors: You should adhere to these recommended practices if you want to manage unhandled failures with Node.js in an efficient manner:

• Any function that even remotely has the potential to generate an error, provides procedures for error handling.
• Make use of error messages that are detailed and give developers information that is helpful to them.
• To record mistakes in a database or log file, you may make use of a logging library.
• Error tracking in production settings may be accomplished with the help of error monitoring technologies such as Sentry, Rollbar, and Bugsnag.
• Do extensive testing on your methods for managing errors to validate that they perform as anticipated.

Conclusion: Your application may crash if it encounters unhandled problems in Node.js, or it may yield outcomes that are unexpected. You will need to create error handling techniques such as try-catch blocks, error handlers, and error handlers and procedures in order to fix unhandled problems.