easyPhone Screen

What is Node.js and why is it popular?

Q: What is Node.js and why is it popular?

**TL;DR.** Node.js is a **runtime** that runs JavaScript outside the browser, built on Chrome's **V8** engine plus **libuv** for non-blocking I/O. Its single-threaded, **event-driven** model handles thousands of concurrent connections cheaply, and "JavaScript everywhere" lets teams share one language across front and back end. Node.js runtime V8 engine runs JS, JIT to machine code l

594 views

Understand the problem

This foundational question assesses a candidate's basic understanding of Node.js.

basicsruntimejavascriptarchitecture

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Stuck? AI Nudge Available

Get a conceptual hint to guide your logic without spoiling the final implementation.

Study the solution

The solution is waiting

Give it an honest attempt first — then compare your thinking with the full walkthrough.

Read the code

A minimal HTTP server in a few lines

import { createServer } from 'node:http';

const server = createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({ hello: 'world', url: req.url }));
});

// Non-blocking: one thread, many concurrent connections.
server.listen(3000, () => console.log('Listening on :3000'));

Join the discussion

Discussion (0)

No responses yet. Be the first to share what you think.

What does NODE_ENV=production actually change and why does it matter?

What is structuredClone and when is it useful in Node.js?