Moderate React Question 105 of 226

What is a custom hook and why write one?

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

PICTURE THIS: STACK VS QUEUE

StackLIFOlast in, first out

QueueFIFOfirst in, first out

Simple meaning

A custom hook is a function starting with use that calls other hooks.

WHY — React instead of guessing?

Why interviewers care about React:

React questions separate people

who only read docs from people who shipped.

Keep it short, concrete,

and tied to Full Stack work.

Stay structured

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

Close cleanly

End with when you use it and one common pitfall.

STEPS — What happens step by step?

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

1
A custom hook is
a function starting with use that calls other hooks.
2
It reuses stateful logic
such as form handling or authenticated fetch without copying useEffect blocks.
3
How it works
It should not return JSX
4
Give an example
that belongs in a component.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

EXAMPLE — See it in action

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

Say this line

“It reuses stateful logic such as form handling or authenticated fetch without co”

Break into beats

Itreusesstatefullogicsuchas

Speaking order

2987408337471632900

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

Key takeaway

A custom hook is a function starting with use that calls other hooks. It reuses stateful logic such as form handling or authenticated fetch without copying useEffect blocks.