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

What is `npm` and what are its core functionalities?

Accepted Answer

npm stands for Node Package Manager. It is the default package manager for Node.js and is used for installing, sharing, and managing project dependencies. Its core functionalities include installing packages from the npm registry, managing project metadata in `package.json`, running scripts defined in `package.json`, and publishing your own packages to the registry. It's crucial for building and maintaining Node.js applications efficiently.

Question 4

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 5

What is the node:util parseArgs helper for building CLIs?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js CLI-tooling interviews. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Both the successful parse and the strict-mode rejection below were **actually run** — real, structured output from a real CLI invocation, and a real thrown error, not descriptions of documented behavior. ## 1. Why This Even Matters — A Story First Reaching for a full-featu

Question 6

What is the purpose of `package-lock.json`?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js phone screens — assumes basic `package.json`/npm familiarity. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The lock-file structure below came from **actually running** `npm install` on this machine and reading the real generated file, not a hand-written example. ## 1. Why This Even Matters — A Story First Two bakers are handed the identical

Question 7

What are npm workspaces and how do you manage a monorepo with them?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js tooling and monorepo-architecture interviews. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The symlink creation and cross-package resolution below were **actually run** — a real `npm install`, real `ls -la` output confirming genuine symlinks, and a genuine live-edit visible through them. ## 1. Why This Even Matters — A Story First Two roo

Question 8

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 9

How do you design liveness and readiness health-check endpoints?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js production-operations and Kubernetes-adjacent interviews. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The real, distinct liveness/readiness responses below were **actually run** — a genuine 200 and a genuine 503 from the identical real dependency outage, not descriptions of documented behavior. ## 1. Why This Even Matters — A Story First

Question 10

How do you containerize a Node.js app with a small, secure Docker image (multi-stage, distroless)?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js deployment/DevOps-adjacent system-design interviews. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The production-vs-full dependency size gap below was **actually measured** in this sandbox via real `npm install` runs. The full Docker image build itself could not be executed in this particular sandbox session (Docker Desktop's engine was not

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?

What is `npm` and what are its core functionalities?

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

What is the node:util parseArgs helper for building CLIs?

What is the purpose of `package-lock.json`?

Medium

What are npm workspaces and how do you manage a monorepo with them?

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

How do you design liveness and readiness health-check endpoints?

How do you containerize a Node.js app with a small, secure Docker image (multi-stage, distroless)?

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

What are some common security best practices in Node.js applications?

Describe the Node.js module system. What are CommonJS and ES Modules?

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.