Express JS Express Error Handling 2

Question 1

How can you create a custom error class with an HTTP status code for use with Express?

Accepted Answer

Extend Error and add a status property

Answer

You can extend the built-in Error class and attach a status property to carry HTTP status codes through the error pipeline.

Question 2

What is the purpose of the http-errors package commonly used with Express?

Accepted Answer

Creates HTTP-specific error objects with status codes and messages

Answer

http-errors creates error objects pre-populated with HTTP status codes, making it easy to send standardized error responses.

Question 3

Which Express middleware pattern handles 404 Not Found errors for unmatched routes?

Accepted Answer

Add a catch-all app.use() at the end that calls next(createError(404))

Answer

A catch-all middleware placed after all routes and before the error handler catches unmatched requests and generates a 404 error.

Question 4

How do you differentiate between development and production error responses in Express?

Accepted Answer

Check process.env.NODE_ENV in the error handler and conditionally include stack traces

Answer

By checking process.env.NODE_ENV, you can expose detailed stack traces in development while sending minimal info in production.

Question 5

What happens to errors thrown synchronously inside a route handler in Express?

Accepted Answer

Express catches them automatically and passes them to the error handler

Answer

Express wraps synchronous route handler code and automatically catches thrown errors, forwarding them to error-handling middleware.

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