Handling uncaught exceptions in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an uncaught exception in Node.js?

An uncaught exception is an error that occurs during program execution but is not handled by any try-catch block or error handler, causing the program to crash if not managed.

beginner

How do you listen for uncaught exceptions in Node.js?

You use the process object's 'uncaughtException' event to listen for errors that were not caught anywhere else in the code.

intermediate

Why should you avoid using 'uncaughtException' for normal error handling?

Because it is a last-resort handler; the application state might be unstable after an uncaught exception, so it's better to log the error and safely shut down the app.

beginner

What is the recommended way to handle errors in asynchronous code in Node.js?

Use try-catch blocks with async/await or handle errors in callbacks/promises instead of relying on 'uncaughtException'.

beginner

Show a simple example of handling an uncaught exception in Node.js.

process.on('uncaughtException', (err) => { console.error('Caught exception:', err); process.exit(1); // Exit to avoid unstable state });

Which Node.js event is used to catch uncaught exceptions?

A 'unhandledRejection'

B 'error'

C 'exceptionCaught'

D 'uncaughtException'

The 'uncaughtException' event on the process object catches exceptions not handled elsewhere.

What should you do after catching an uncaught exception?

A Log the error and safely shut down the application

B Ignore the error

C Log the error and continue running normally

D Restart the Node.js process automatically

After an uncaught exception, the app might be unstable, so it's best to log and exit safely.

Which of these is NOT a good practice for error handling in Node.js?

A Using try-catch in async functions

B Relying only on 'uncaughtException' for all errors

C Handling promise rejections properly

D Using callbacks with error parameters

'uncaughtException' should be a last resort, not the main error handling method.

What happens if an uncaught exception is not handled in Node.js?

A The program logs the error and continues

B The program continues silently

C The program crashes immediately

D The program restarts automatically

Without handling, uncaught exceptions cause the Node.js process to crash.

Which event is used to catch unhandled promise rejections in Node.js?

A 'unhandledRejection'

B 'rejectionHandled'

C 'error'

D 'uncaughtException'

'unhandledRejection' event handles promises rejected without catch.

Explain how to handle uncaught exceptions in Node.js and why it is important.

Think about what happens if an error is not caught and how Node.js lets you listen for it.

Describe best practices for error handling in asynchronous Node.js code compared to using uncaughtException.

Consider how errors flow in async code and how to catch them early.