Node.js: practice, test and prove it

Node.js event loop, CommonJS and ES modules, npm, async code, Express middleware, errors and env variables.

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Start the node.js test Read the first lesson

Node.js screenings usually mix output prediction with practical API questions. Expect a few lines of timers and promises where you must give the exact log order, a module that exports the wrong thing, and an Express app where a request hangs or skips a route. Many also ask about package.json, semver ranges and keeping secrets out of code.

This page gives you that mix to practise. The lessons explain the event loop and the request pipeline in Express, which together cover most of what these tests check.

Benchmark: The pass mark is 80%, and this skill is commonly screened for back-end developer, Node.js developer, API developer and full-stack roles. Requirements vary by employer.

Lessons

The event loop, modules and async codePredict the order of logs, timers and promises, and load modules correctly in CommonJS and ES module projects.Lesson 1

Express routing, middleware, errors and configFollow a request through Express middleware, handle errors in one place, and keep configuration in environment variables.Lesson 2

Working with files, paths and streams in Node.jsRead and write files with fs.promises, build paths that work on any machine, and stream large files instead of loading them.Lesson 3

npm, package.json, scripts and semantic versioningRead a package.json with confidence, know what ^ and ~ allow, and use the lockfile and npm ci so installs match everywhere.Lesson 4

Interview prep

Node.js interview questionsQuestions often used to check whether a candidate understands how Node handles concurrency and how an Express service is put together.6 questions

Certificate

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Common questions

Do the questions use CommonJS or ES modules?

Both appear, because real projects use both. Each question states the module type when it matters, so read the package.json detail carefully.

Is Express the only framework covered?

Express is used for routing and middleware questions because its model is simple and widely known. The ideas of ordered middleware and central error handling carry over to most Node frameworks.

Do I need to know Node internals like libuv?

Not in detail. You should know that your JavaScript runs on one thread, that slow input and output happen in the background, and in what order callbacks come back.

Node.js test for interviewWhat the screening round looks like, with a 5-question sample.