Moderate Express Question 87 of 226

How do you add a central error handler in Express?

MERN Full Stack · Speak this in 60–90 seconds · Faridabad & Delhi NCR

StackLIFOlast in, first out

QueueFIFOfirst in, first out

Why interviewers care about Express:

This is a process

question about Express.

Panels listen for order,

trade-offs, and what you would actually do on a Full Stack project - not buzzwords.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
Register a four-argument middleware
last: err, req, res, next.
2
Async routes must call
next(err) so that handler runs.
3
It should log the
error, hide internals in production, and return a consistent JSON error body.
4
Give an example
One tiny concrete case you can say aloud.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“Async routes must call next(err) so that handler runs.”

Break into beats

Asyncroutesmustcallnexterr

Speaking order

2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.