Tooling & Package Management

Question 1

What is npm?

Answer 1

npm (Node Package Manager) is the default package manager for Node.js that manages dependencies and scripts for JavaScript projects.

Question 2

What is Yarn?

Answer 2

Yarn is an alternative package manager to npm, developed by Facebook, known for faster installs and deterministic dependency resolution.

Question 3

What is the purpose of a package.json file?

Answer 3

The package.json file contains metadata about a project and manages dependencies, scripts, and project configuration.

Question 4

What is a package-lock.json or yarn.lock file?

Answer 4

These files lock the dependency tree to specific versions, ensuring consistent installs across environments.

Question 5

What are environment variables?

Answer 5

Environment variables are dynamic values that can affect the way running processes behave, commonly used for configs like API keys.

Question 6

What is dotenv?

Answer 6

dotenv is a zero-dependency module that loads environment variables from a .env file into process.env.

Question 7

What is cross-env?

Answer 7

cross-env allows setting environment variables in scripts across platforms (Windows, Linux, macOS).

Question 8

What is linting in JavaScript?

Answer 8

Linting is the process of statically analyzing code to find bugs, style issues, or bad practices using tools like ESLint.

Question 9

What is Prettier?

Answer 9

Prettier is an opinionated code formatter that enforces a consistent code style across your project.

Question 10

What is the benefit of using linting tools?

Answer 10

They help enforce code quality and consistency, prevent bugs, and make code easier to maintain.

Question 11

What are npm scripts?

Answer 11

npm scripts are custom commands defined in the package.json file that can automate tasks like build, test, or lint.

Question 12

What are lifecycle hooks in npm?

Answer 12

Lifecycle hooks are special npm script names that automatically run at specific points like install, start, or test.

Question 13

How do you define a start script in npm?

Answer 13

In package.json: "scripts": { "start": "node index.js" }

Question 14

What is the advantage of using Yarn over npm?

Answer 14

Yarn offers faster and more reliable installations, caching, and offline support.

Question 15

What is a disadvantage of using Yarn?

Answer 15

Yarn adds another layer of tooling, which may complicate workflows for teams already using npm.

Question 16

What is a best practice for managing env configs?

Answer 16

Store secrets in .env, use dotenv to load them, and never commit .env files to version control.

Question 17

What is a use case for cross-env?

Answer 17

Ensuring scripts that set environment variables work across platforms (e.g., setting NODE_ENV in Windows).

Question 18

What impact do scripts have on system design?

Answer 18

Scripts help standardize and automate repetitive tasks like linting, testing, or deployment, aiding CI/CD pipelines.

Question 19

Give an example of a lint script.

Answer 19

"lint": "eslint ."

Question 20

Give an example of using cross-env in scripts.

Answer 20

"scripts": { "start": "cross-env NODE_ENV=production node app.js" }

Question 21

What architectural benefit do linting tools provide?

Answer 21

They promote clean, maintainable codebases and support scalable development by enforcing rules.

Question 22

How can tooling improve performance and fault tolerance?

Answer 22

By catching issues early with linting and environment configs, and reducing errors in production builds.

Question 23

How do you monitor tooling setup in CI/CD pipelines?

Answer 23

Run lint, test, and build scripts as part of CI jobs; log outputs and enforce failures on issues.

Question 24

What are some real-world tradeoffs with tooling?

Answer 24

Tooling adds overhead and setup time but improves consistency and reduces bugs in the long run.

Question 25

What is a common interview question about npm?

Answer 25

What is the difference between dependencies and devDependencies in package.json?

Question 26

What’s a gotcha when using dotenv?

Answer 26

dotenv only loads variables at runtime, so changes in `.env` don't apply until the server restarts.

Question 27

What’s a gotcha when using scripts with environment variables on Windows?

Answer 27

Setting env vars directly fails; use cross-env to ensure compatibility.

Question 28

What’s the role of devDependencies?

Answer 28

Packages only needed for development (e.g., testing, linting tools) are listed in devDependencies.

Question 29

What’s the difference between `npm install` and `npm ci`?

Answer 29

`npm install` installs dependencies, possibly modifying package-lock; `npm ci` installs exactly what's in lock file and is used in CI.

Question 30

Why use Prettier over ESLint for formatting?

Answer 30

Prettier is opinionated and enforces consistent formatting automatically; ESLint is more focused on code quality and best practices.

Question 31

What’s the difference between ESLint and Prettier?

Answer 31

ESLint finds potential problems in code, while Prettier formats code for style and consistency.

Question 32

What is a common .npmrc configuration?

Answer 32

You can use .npmrc to configure registry, cache, and authentication settings for npm installs.

Question 33

What is a potential issue with conflicting ESLint and Prettier rules?

Answer 33

They can contradict each other; use eslint-config-prettier to disable formatting rules in ESLint.

Question 34

Why is script standardization important in teams?

Answer 34

It ensures everyone uses the same commands and setups, reducing onboarding time and preventing errors.

Question 35

What is a recommended structure for env configs?

Answer 35

Use `.env`, `.env.development`, `.env.production`, and load them conditionally based on NODE_ENV.

Question 36

What’s the impact of tooling on debugging?

Answer 36

Better tooling helps catch syntax and logic errors early, reducing time spent debugging.

Question 37

What is the purpose of `npx`?

Answer 37

npx runs binaries from npm packages without globally installing them.

Question 38

What’s a disadvantage of over-configuring tooling?

Answer 38

It can slow down the development process and create steep learning curves for new developers.

Question 39

What’s a good practice for Prettier and ESLint setup?

Answer 39

Integrate them with your editor and run them in pre-commit hooks or CI.

Question 40

What are husky and lint-staged used for?

Answer 40

husky sets up Git hooks, and lint-staged runs linters on staged files before committing to improve code quality.

Question 41

How do you enforce script consistency across devs?

Answer 41

Use scripts in `package.json` and optionally enforce with tools like `npm-run-all` or custom shell scripts.

Question 42

What is a typical use case for npm lifecycle scripts?

Answer 42

Run build steps before starting the server or cleaning directories before testing.

Question 43

What is the difference between `npm run` and running a script directly?

Answer 43

`npm run` uses the local node_modules/.bin path, making locally installed tools available without global install.

Question 44

Why should you not commit `.env` files?

Answer 44

They can contain sensitive data like API keys and credentials, which should not be exposed publicly.

Question 45

What’s the use of `.env.example`?

Answer 45

It provides a template for required env variables without exposing actual secrets.

Question 46

What happens if a required env var is missing?

Answer 46

Your app might crash or behave unexpectedly; always validate required env vars on startup.

Question 47

What’s the difference between `npm uninstall` and `npm remove`?

Answer 47

They are aliases; both remove a package from node_modules and package.json.

Question 48

What are peerDependencies?

Answer 48

peerDependencies are used when a package expects a specific version of another package to be installed by the consumer.

Question 49

What is the advantage of using lock files in npm/yarn?

Answer 49

They ensure consistent dependency versions across different environments and installations.