Moderate React Question 126 of 229

What is a custom hook and when would you write one?

Frontend Master · Speak this in 60–90 seconds · Faridabad & Delhi NCR

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Simple meaning

A custom hook is a function starting with use that calls other hooks, so I can reuse stateful logic.

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 Frontend 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, so I can reuse stateful logic.
2
UseAuth, useDebouncedValue, and useMediaQuery
are typical.
3
I extract one when
two components copy the same effect and state, not on the first line of a screen.
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.

EXAMPLE — See it in action

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

Say this line

“UseAuth, useDebouncedValue, and useMediaQuery are typical.”

Break into beats

UseAuthuseDebouncedValueanduseMediaQueryaretypical

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, so I can reuse stateful logic. UseAuth, useDebouncedValue, and useMediaQuery are typical.