What is an error boundary?
PICTURE THIS: ASYNC / PROMISE
Simple meaning
An error boundary is a class component that catches render errors in its children and shows a fallback UI.
WHY — React instead of guessing?
Why interviewers care about React:
who only read docs from people who shipped.
and tied to Frontend work.
Name the idea, why it exists, then one short example.
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:
- 1An error boundary is
a class component that catches render errors in its children and shows a fallback UI.
- 2It does not catch
errors in event handlers, async code, or the boundary itself.
- 3In production I wrap
route-level chunks so one crash does not white-screen the whole app.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
An error boundary is a class component that catches render errors in its children and shows a fallback UI. It does not catch errors in event handlers, async code, or the boundary itself.