# npm
npm init                    # interactive prompts
npm init -y                 # accept all defaults

# Yarn
yarn init
yarn init -y

# npm
npm install                          # install all from package.json
npm install lodash                   # add runtime dependency
npm install --save-dev jest          # add dev dependency
npm install -D typescript            # shorthand for --save-dev
npm install -g nodemon               # global install
npm install lodash@4.17.21           # specific version
npm install lodash@^4.0.0            # semver range

# Yarn
yarn                                 # install all
yarn add lodash                      # add runtime
yarn add --dev jest                  # add dev dependency
yarn add -D typescript               # shorthand
yarn global add nodemon              # global
yarn add lodash@4.17.21              # specific version

npm uninstall lodash
npm uninstall --save-dev jest
npm uninstall -g nodemon

yarn remove lodash

# npm
npm update                       # update all (respects semver range)
npm update lodash                # update specific package
npm outdated                     # list outdated packages
npx npm-check-updates -u         # upgrade all to latest (ignores semver)

# Yarn
yarn upgrade                     # update all
yarn upgrade lodash              # update specific
yarn upgrade lodash --latest     # update to latest (ignore semver)
yarn outdated                    # list outdated

# package.json scripts:
# "scripts": { "build": "tsc", "test": "jest", "dev": "ts-node src/index.ts" }

npm run build
npm run test
npm test               # shorthand for npm run test
npm start              # shorthand for npm run start

yarn build
yarn test
yarn dev

# npm — pass arguments to scripts
npm run test -- --watch
npm run build -- --mode production

npm list                           # all installed packages
npm list --depth=0                 # top-level only
npm list lodash                    # check if installed
npm info lodash                    # registry info
npm info lodash versions           # all published versions

yarn list
yarn list --depth=0
yarn info lodash

// package.json (root)
{
  "name": "my-monorepo",
  "private": true,
  "workspaces": ["packages/*", "apps/*"]
}

# npm workspaces
npm install                            # install all workspaces
npm install lodash -w packages/utils   # install in specific workspace
npm run build -w packages/core         # run script in workspace
npm run build --workspaces             # run in all workspaces

# Yarn workspaces
yarn workspaces run build              # run build in all workspaces
yarn workspace packages/utils add axios

# Login
npm login
npm whoami                      # verify logged in

# Publish
npm publish                     # publish (uses version in package.json)
npm publish --access public     # for scoped packages (@user/pkg)
npm version patch               # 1.0.0 → 1.0.1
npm version minor               # 1.0.0 → 1.1.0
npm version major               # 1.0.0 → 2.0.0
npm deprecate my-pkg@1.0.0 "Use v2"

# Dry run
npm publish --dry-run

npx create-react-app my-app           # run without installing globally
npx create-next-app@latest my-app
npx tsc --init                        # TypeScript config
npx prettier --write .                # format codebase
npx eslint --fix src/                 # lint and fix
npx npm-check-updates                 # check for updates without changing files

# .npmrc (project or global ~/.npmrc)
registry=https://registry.npmjs.org/
save-exact=true              # pin exact versions (no ^ or ~)
engine-strict=true           # fail if Node version doesn't match engines field
fund=false                   # suppress funding messages
audit=false                  # skip audit on install (CI speed)

npm ci               # clean install from lock file (CI/CD standard)
npm install          # can update lock file; developer workflow