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 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 3

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 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 semantic versioning and how do ^, ~, and exact versions behave?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js dependency-management interviews. **Difficulty:** Easy > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Every range check below was **actually run** with the real `semver` package — genuine `true`/`false` results, not a description of the spec. ## 1. Why This Even Matters — A Story First A promise to "only ever make the recipe spicier or add a garnish, never change

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 is the difference between "type": "module", .mjs, and .cjs?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js module-system interviews — assumes basic familiarity with CommonJS `require()` and ESM `import`. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Every behavior below was **actually run** on Node v24.19.0 in a real project directory — genuine console output and a genuine real error message, not descriptions of intended behavior. ## 1. Why This

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

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

Accepted Answer

**Target Audience:** Engineers preparing for Node.js phone screens — assumes basic `import`/`export` syntax familiarity. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. Every interop claim below was **actually executed** on Node v24.19.0, including a genuinely surprising interop detail found while testing rather than assumed. ## 1. Why This Even Matters — A Story First Two countries share a bo

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