A Quick Introduction to the Yarn Package Manager

There are a few ways to install Yarn. You can, ironically enough, install it through npm:

npm install -g yarn

If you don’t have npm installed, you can also install with a simple bash script:

curl -o- -L https://yarnpkg.com/install.sh | bash

On Windows, you can get an installer file here.

Run this to see if Yarn was properly installed or to see if you have the latest version:

yarn --version

To initialize a new project, run yarn init:

yarn init

Here’s how to install all the dependencies from your package.json file (the equivalent of npm install):

yarn

Let’s use lodash for most of our examples:

Adding a project dependency

Use the add command to add a dependency to your project:

yarn add lodash

You will see an output like this:

Output
yarn add v1.22.5
info No lockfile found.
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 🔨  Building fresh packages...
success Saved lockfile.
success Saved 1 new dependency.
info Direct dependencies
└─ lodash@4.17.20
info All dependencies
└─ lodash@4.17.20
✨  Done in 1.48s.

Use the --dev (or its alias -D) flag to add a package as a dev dependency:

yarn add babel-cli -D

Updating a dependency

yarn upgrade lodash

or upgrade all the dependencies:

yarn upgrade

Removing a dependency

yarn remove lodash

Adding a global dependency

yarn global add lodash

This is a basic introduction to the Yarn Package Manager. Here are some other common commands:

• Get some information about a package: yarn info lodash
• Verify that the installed version of a package is a match between the package.json and the Yarn lock files: yarn check
• Publish a package: yarn publish
• Check for outdated packages: yarn outdated
• Find why a package is needed: yarn why lodash
• Run one of the scripts defined in package.json: yarn run test

Have fun with Yarn!