Node.js Production Pitfalls — 36 bugs interviewers love to ask about

Senior backend interviews rarely ask what an API does. They describe a service that broke in production and ask why, how you'd find it, and how you'd fix it. This workbook covers 36 of those Node.js failures, the kind that pass code review, work on your laptop and break under real traffic.

Every pitfall gets two pages:

- An infographic that shows the bug at a glance: what runs when, which line is wrong, or how the parts connect

- A full explanation: what's wrong, why it happens, the fix with code, the follow-up question an interviewer asks next with a model answer, and a drill to run on your own codebase

What's covered: 36 pitfalls across 6 areas, including:

- Event loop and performance: blocking the event loop, CPU work on the main thread, huge JSON parsing, ReDoS, nextTick starvation, unbounded concurrency

- Errors and process lifecycle: unhandled rejections, missing 'error' listeners, process.exit() in request code, no graceful shutdown on SIGTERM, lost stack traces

- Architecture and config: logic in route handlers, hardcoded config and secrets, module-level state leaking between users, circular requires

- Data, I/O and network: connection-per-request, pool leaks, missing pagination, not streaming, ignoring backpressure, no timeouts, retry storms, keep-alive 502s behind load balancers

- Security: unvalidated input, stack traces in responses, no rate limiting, path traversal, command injection, supply-chain risk

- Operations: wrong status codes, console.log as logging, memory leaks, missing health checks, using one CPU core

Also inside:

✓ A pitfall map at the front showing all 36 pitfalls by area

✓ Fillable drill boxes: type in any PDF reader, or print and write

✓ A review tracker to tick off each pitfall as you master it

✓ Written for Node.js 24 LTS

Who it's for:

backend and full-stack developers preparing for mid-level to senior interviews, and anyone running Node.js in production who wants to catch these bugs before users do.

Companion to the Node.js Interview Workbook: that book covers the concepts, this one covers the bugs they cause.

Format: PDF, 85 pages, instant download.