How do you handle errors in asynchronous Node.js code?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of Node.js conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
For promises and async functions use try/catch and let errors propagate to a central handler:
app.get('/users/:id', asyncHandler(async (req, res) => {
const user = await repo.find(req.params.id);
if (!user) throw new NotFoundError();
res.json(user);
}));
Patterns:
- asyncHandler wraps async routes so rejected promises reach Express error middleware.
- Distinguish operational errors (bad input, network) from programmer errors; only operational errors should be retried/reported to users.
- Attach handlers to streams (.on('error')), EventEmitters and process level 'unhandledRejection'/'uncaughtException' as a last resort, then exit cleanly.
- Use a structured logger and never leak stack traces to clients.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.