Node.js Interview Questions

The event loop is the foundation of everything in Node.js. If a developer doesn't understand it, they'll write blocking code that kills throughput and won't know why.

The CJS/ESM split causes real confusion in Node.js projects. This shows whether the candidate understands module systems or just copies import syntax without knowing why things break.

Reveals whether the candidate understands blocking I/O and memory implications, which are the two things that crash Node.js servers in production.

Unhandled promise rejections crash Node.js processes. This is a quick way to find out if the candidate writes production-safe async code or leaves error handling as an afterthought.

Shows if the candidate has opinions about code organization or just puts everything in one file until it breaks.

Developers who rely only on console.log for debugging will struggle with complex production issues. This surfaces their actual debugging workflow.

Tests event loop understanding beyond the basics. Candidates who confuse these two will write subtle timing bugs in production code.