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Node.js

Node.js practice

Blocking the loop

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One request handler runs a 2-second CPU loop. What happens to other requests meanwhile?

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No signup · first signal after 5 answers · your score at session end

Master the runtime behind server-side JavaScript

How Node.js really works — the libuv event loop and its phases, microtasks vs timers (process.nextTick, setImmediate), non-blocking I/O and the thread pool, streams and buffers, CommonJS vs ES modules, async patterns and error handling, EventEmitter, worker_threads for CPU-bound work, and building/operating servers. Evergreen fundamentals (reference: Node 24 LTS) that senior backend interviews assume. Part of the Developer track.

• Meets you at your level — never too easy, never too hard.

• Adapts every question to how you’re doing.

• Tracks your level over time. Skill practice, not a test.

New here? Read the Node.js guide

A free 18-minute primer — the mental model, the mistakes beginners make, and what to practice first.

Curriculum

231 concepts across 26 chapters, from foundations through advanced practice — each one a concept the adaptive question bank can teach and test.

A. The runtime: what Node adds to JavaScript

B. The event loop, timers and scheduling

C. The process: arguments, environment and lifecycle

D. CommonJS modules

E. ESM, package.json and module resolution

F. EventEmitter and the event pattern

G. Errors and asynchronous failure

H. Buffers and binary data

I. Streams and backpressure

J. Web streams and cross-standard interop

K. The file system

L. Paths, URLs and name handling

M. HTTP servers and clients

N. TCP, UDP, TLS and DNS

O. Child processes

P. worker_threads and multi-process scaling

Q. Cancellation and asynchronous context

R. Cryptography

S. The permission model and hardening

T. Diagnostics, profiling and memory

U. Testing with node:test

V. The CLI, flags and configuration

W. Modern Node: TypeScript, SQLite, packaging and releases

X. The rest of the standard toolkit

Y. HTTP/2

Z. Reading input line by line

View the full curriculum →

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Node.js on exams

Node.js is one of the skills tested on this exam. Each prep page lays out what the real test covers and where this skill fits.

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