Node.js NPM & Package Management 3 — Questions and Answers
Question 1: Which npm script lifecycle hook runs automatically BEFORE the `build` script?
- prebuild (Correct answer)
- beforebuild
- setup
- preinstall
Correct answer: prebuild
npm automatically runs a script named `prebuild` before the `build` script, following the `pre<scriptname>` convention.
Question 2: What does the caret (`^`) range in `"express": "^4.18.0"` allow?
- Only the exact version 4.18.0
- Any version >=4.18.0 and <5.0.0 (Correct answer)
- Any version >=4.0.0
- Any version >=4.18.0 and <4.19.0
Correct answer: Any version >=4.18.0 and <5.0.0
The caret allows compatible updates: it pins the major version and allows minor and patch updates, so `>=4.18.0 <5.0.0`.
Question 3: How do you run a locally installed CLI tool (in node_modules/.bin) without adding it to PATH?
- npm exec
- npx (Correct answer)
- node_modules run
- npm start
Correct answer: npx
`npx <tool>` executes a binary from node_modules/.bin (or downloads it temporarily) without needing a global install.
Question 4: What command publishes a package to the npm registry?
- npm push
- npm deploy
- npm publish (Correct answer)
- npm release
Correct answer: npm publish
`npm publish` uploads the package to the registry, making it available for others to install.
Question 5: Which field in package.json specifies the entry point file of a Node.js module?
- start
- index
- main (Correct answer)
- entry
Correct answer: main
The `main` field defines the file that is loaded when the package is `require()`d by another module.
Question 6: What does `npm link` do?
- Creates a symlink from node_modules to a local package for development (Correct answer)
- Links two npm accounts together
- Publishes a package under an alias
- Installs a package from a git URL
Correct answer: Creates a symlink from node_modules to a local package for development
`npm link` creates a global symlink for a local package, then `npm link <pkg>` in another project symlinks to it for local development testing.
Question 7: What does the `engines` field in package.json specify?
- The build tools required
- The compatible Node.js and npm version ranges the package supports (Correct answer)
- The operating systems the package runs on
- The JavaScript engine internals used
Correct answer: The compatible Node.js and npm version ranges the package supports
The `engines` field declares which Node.js (and optionally npm) versions the package is compatible with, and npm warns if the running version doesn't match.
Node.js NPM & Package Management 3
Which npm script lifecycle hook runs automatically BEFORE the `build` script?