Yarn

Installation and Setup

Yarn’s docs install it through Corepack, a small tool that downloads the Yarn release a project asks for. Node.js 26 doesn’t ship Corepack, so install it from npm first and then turn on its yarn command:

$ npm install -g corepack
$ corepack enable

Outside a project, this yarn command runs Yarn Classic. The init -2 command creates a new project that uses the latest modern release:

$ mkdir shop
$ cd shop
$ yarn init -2
$ yarn --version
4.18.1

The command also writes a packageManager field such as "[email protected]" into package.json, which is how Corepack knows which release to run.

Key Features

• Pins the Yarn release for each project through the packageManager field in package.json.
• Installs with Plug’n’Play by default, which writes a .pnp.cjs loader instead of a node_modules folder.
• Switches back to a classic node_modules folder with the nodeLinker: node-modules setting in .yarnrc.yml.
• Manages monorepos through workspaces declared in the root package.json.
• Runs a package’s command once, without adding it to the project, through yarn dlx.

Usage

Say a new shop project needs Prettier to format its code. The add command with -D installs Prettier and saves it under devDependencies:

$ yarn add -D prettier
➤ YN0000: · Yarn 4.18.1
➤ YN0000: ┌ Resolution step
➤ YN0085: │ + prettier@npm:3.9.10
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0013: │ A package was added to the project (+ 9.5 MiB).
➤ YN0000: └ Completed in 0s 423ms
➤ YN0000: ┌ Link step
➤ YN0000: └ Completed
➤ YN0000: · Done in 0s 568ms

A script in package.json gives the formatter a short name:

{
  "scripts": {
    "format": "prettier --write ."
  }
}

Yarn runs a script given only its name, so yarn format works as a shortcut for yarn run format:

$ yarn format
cart.js 41ms
package.json 3ms (unchanged)
README.md 31ms (unchanged)

After cloning the project, a teammate runs yarn with no arguments to install every dependency at the versions in the lockfile:

$ yarn

The up command upgrades a dependency across the whole project, including every workspace:

$ yarn up prettier

The dlx command downloads a package into a temporary environment and runs its command once:

$ yarn dlx create-vite my-app

For every command and setting, see the Yarn documentation.