npm package manager 🤖 ¶

npm (7.4k ⭐) is the most well-known package manager for Node.js, as it comes bundled with the official Node.js installer.

$ npm install -g npm
$ npm -v

• See the documentation here.
• Use npmjs to find packages (Registry API).

npm uses a file called package.json to know which packages to import into your project. As versions are usually based on a rule, the exact version of the package can be found in package-lock.json.

New Project ¶

Create an empty project with an empty package.json.

$ npm init

All installed packages are stored in the folder node_modules. Add it to your .gitignore, because it's heavy and useless. ⚠️

Instead, commit package-lock.json. Someone else will be able to generate back the same node_modules with a command.

➡️ Commit package.json too, so that devs can add packages...

Existing Project ¶

Install packages from an existing project (package-lock.json).

$ npm ci
$ npm ci --production # only non-dev packages

Update dependencies ¶

Add packages in package.json/dependencies and install them.

# add in package.json/dependencies + install it
$ npm i express                  # 🤔
$ npm install express            # ✅
$ npm install xxx -D             # install as dev package
$ npm install xxx --save-dev     # same

# generate package-lock.json from package.json
$ npm install                    # all packages
$ npm install --production       # only non-dev packages

# Update package-lock.json
$ npm update

# when used with "i", use "@" followed by the "version"
$ npm i express@latest

➡️ If you see an example with require('xxx'), then it's rather safe to assume that you can use npm i xxx.

Add scripts ¶

Usually, we store the commands to run/test... a project in package.json/scripts. To run "start" below, use npm start.

{
  "scripts": {
    // "npm start" will run "node index.js"
    "start": "node index.js"
  }
}

• npx
• .npmignore
• --save / -S (before ~2017, npm install didn't add the dependency in package.json)
• -g (+not recommended)

• npm config
• npm config set xxx yyy
• npm --arch=xxx --target_arch=xxx
• npm outdated
• npm prune
• npm cache add + npm install --no-registry