Question 1

What is the difference between dependencies, devDependencies, and peerDependencies?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js phone screens — assumes basic npm familiarity. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The install behavior below came from **actually running** `npm install --save-dev` and a subsequent `npm install --omit=dev` on this machine, not a description of expected behavior. ## 1. Why This Even Matters — A Story First A moving company packs t

Question 2

What does the Node.js --watch flag do and how does it replace nodemon?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js developer-tooling interviews. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The restart-with-a-new-PID below was **actually observed** from a real running `node --watch` process after a real file edit — not a description of documented behavior. ## 1. Why This Even Matters — A Story First Manually killing a terminal process and re-typing the

Question 3

How do you run Node.js processes as a background service?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js/DevOps phone screens — assumes very basic `child_process`/Unix process familiarity. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The detached-process survival below was **actually run** on this machine, with a real log file confirming the child kept working after its parent had already exited. ## 1. Why This Even Matters — A Story First A c

Question 4

What is npx and how does it differ from a global install?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js/npm tooling interviews. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The local-resolution behavior below was **actually run** — a real resolved file path, and a real, immediately-checked `npm ls -g` confirming nothing was installed globally, not a description of intended behavior. ## 1. Why This Even Matters — A Story First Borrowing a spec

Question 5

What is Corepack and how does it manage npm, Yarn, and pnpm versions?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js tooling interviews — assumes basic npm/Yarn/pnpm familiarity. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The tool's bundled availability was **executed on Node v24.19.0** on this machine. ## 1. Why This Even Matters — A Story First Two chefs are handed the same recipe card. One reads it using a set of measuring spoons calibrated to imperi

Question 6

What is Node.js and why is it popular?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js phone screens — no prior Node knowledge assumed. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The version numbers below were read directly from a running Node process on this machine, not quoted from memory. ## 1. Why This Even Matters — A Story First Before Node.js, JavaScript lived almost entirely in one place: the browser, running whatev

Question 7

Explain the purpose of `package.json` and `npm`.

Accepted Answer

**Target Audience:** Engineers preparing for Node.js phone screens — no prior npm experience assumed. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The file contents below came from **actually running** `npm init -y` and `npm install` on this machine, not a hand-written example. ## 1. Why This Even Matters — A Story First A shopping list says "a loaf of bread" — not the specific loaf, not whic

Question 8

When would you choose Node.js over other backend technologies?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js system-design interviews — assumes familiarity with Node's concurrency model (see the dedicated question). **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. This is a judgment-and-trade-off question; the technical claims it rests on are grounded in real measurements verified in their own dedicated questions, cited here rather than re-derived. #

Question 9

What are the differences between npm, Yarn, and pnpm?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js tooling and package-management interviews. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The hoisting difference below was **actually verified** with a real file-existence check on two genuinely separate real installs — not a description of documented behavior. ## 1. Why This Even Matters — A Story First A messy shared closet where anyone

Question 10

How do you run TypeScript directly in Node.js (native type stripping, tsx, ts-node)?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js/TypeScript tooling interviews. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Both the success and the failure below were **actually run** on Node v24.19.0 — a real, unmodified `.ts` file executing correctly with zero flags, and a real, specific error for a genuine TS enum, not descriptions of documented behavior. ## 1. Why This Even Matters

NODE.JSDECODED.

Easy

What is the difference between dependencies, devDependencies, and peerDependencies?

What does the Node.js --watch flag do and how does it replace nodemon?

How do you run Node.js processes as a background service?

What is npx and how does it differ from a global install?

What is Corepack and how does it manage npm, Yarn, and pnpm versions?

What is Node.js and why is it popular?

Explain the purpose of `package.json` and `npm`.

Medium

When would you choose Node.js over other backend technologies?

What are the differences between npm, Yarn, and pnpm?

How do you run TypeScript directly in Node.js (native type stripping, tsx, ts-node)?

What is the built-in node:test runner and how does it compare to Jest and Mocha?

Hard

How do you handle circular dependencies in Node.js?

What are Single Executable Applications (SEA) in Node.js?

Explain 'dependency injection' and how it can be used in Node.js.

What is the 'vm' (Virtual Machine) module and when would you use it?