What are the key Node.js security best practices?
Use JWT in HTTP-only cookies (not localStorage), bcrypt for passwords (with salt and cost factor), express-mongo-sanitize for NoSQL injection prevention, helmet for security headers, express-rate-limit for rate limiting, input validation, CORS with specific origins, and HTTPS with Let's Encrypt. Never hardcode secrets use environment variables.
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More FAQs in Top 50 Node.js Interview Questions Complete Summary and Quick Reference
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).
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.
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