Handling uncaught exceptions in Node.js - Mini Project: Build & Apply

Handling uncaught exceptions in Node.js

📖 Scenario: You are building a simple Node.js application that runs some code which might throw errors. You want to make sure your app does not crash unexpectedly and logs any uncaught exceptions gracefully.

🎯 Goal: Learn how to set up a global handler for uncaught exceptions in Node.js to catch errors that are not handled elsewhere in your code.

📋 What You'll Learn

Create a basic Node.js script with a function that throws an error

Add a configuration variable to control error logging

Use process.on('uncaughtException') to catch uncaught errors

Log the error message and exit the process gracefully

💡 Why This Matters

🌍 Real World

In real Node.js applications, uncaught exceptions can cause the app to crash unexpectedly. Handling them globally helps keep the app stable and logs useful error information.

💼 Career

Knowing how to handle uncaught exceptions is essential for backend developers to build reliable and maintainable Node.js services.

1

Create a function that throws an error

Create a function called riskyOperation that throws a new Error with the message 'Something went wrong!'.

Node.js

// Your code here
// Create the riskyOperation function that throws an error

Need a hint?

Use function riskyOperation() { throw new Error('Something went wrong!'); } to define the function.

2

Add a configuration variable for error logging

Add a constant variable called logErrors and set it to true to control whether errors should be logged.

Node.js

function riskyOperation() {
    throw new Error('Something went wrong!');
}

// Add the logErrors variable below
// Your code here

Need a hint?

Use const logErrors = true; to create the configuration variable.

3

Set up the uncaughtException event handler

Use process.on('uncaughtException', handler) to catch uncaught exceptions. The handler function should accept an error parameter. Inside the handler, if logErrors is true, log the error message using console.error.

Node.js

function riskyOperation() {
    throw new Error('Something went wrong!');
}

const logErrors = true;

// Add the uncaughtException handler below
// Your code here

Need a hint?

Use process.on('uncaughtException', (error) => { if (logErrors) { console.error('Uncaught Exception:', error.message); } });

4

Call the risky function and exit gracefully

Call the riskyOperation() function. Inside the uncaughtException handler, after logging the error, add process.exit(1); to exit the program with an error code.

Node.js

function riskyOperation() {
    throw new Error('Something went wrong!');
}

const logErrors = true;

process.on('uncaughtException', (error) => {
    if (logErrors) {
        console.error('Uncaught Exception:', error.message);
    }
    // Exit the process with code 1
    // Your code here
});

// Call the riskyOperation function below
// Your code here

Need a hint?

Call riskyOperation(); and add process.exit(1); inside the handler to exit after logging.