What are the most important Node.js interview topics?
Event loop (phases, microtasks, single-thread), modules (require/import, caching, circular deps), async programming (callbacks, Promises, async/await), Express (middleware, error handling, Router), MongoDB/Mongoose (schemas, indexes, populate, aggregation), security (JWT, bcrypt, injection, headers), and performance (clustering, streams, worker threads, memory, query optimization).
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More FAQs in Top 50 Node.js Interview Questions Complete Summary and Quick Reference
The event loop how it works, its phases (timers, poll, check, close), the difference between setTimeout/setImmediate/process.nextTick, and why Node.js is single-threaded. Understanding the event loop is essential for any Node.js developer.
Study the event loop (phases, microtasks vs macrotasks), async programming (Promises, async/await, Promise.all), Express (middleware, error handling), MongoDB (indexes, populate, aggregation), security (JWT, bcrypt, NoSQL injection), performance (clustering, streams, worker threads), and deployment (PM2, Nginx, Docker, CI/CD). Practice coding questions.
Execution order: process.nextTick (after current operation, before next phase), Promise.then (microtask, after nextTick), setTimeout (timers phase), setImmediate (check phase, after I/O). nextTick and Promise are microtasks that run between phases; setTimeout and setImmediate are macrotasks that run in specific phases.
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