Updated Jan 23 2019
It’s compatible with npm packages, so it has the great advantage of being a drop-in replacement for npm.
When it launched it used to be way faster than
npm due to parallel download and caching, but now
npm did catch up with many of its features and is now the solution I recommend.
Tools eventually converge to a set of features that keeps them on the same level to stay relevant, so we’ll likely see those features in npm in the future - competition is nice for us users.
While you can install Yarn with npm (
npm install -g yarn), it’s not recommended by the Yarn team.
System-specific installation methods are listed at https://yarnpkg.com/en/docs/install. On macOS for example you can use Homebrew and run
brew install yarn
but every Operating System has its own package manager of choice that will make the process very smooth.
In the end, you’ll end up with the
yarn command available in your shell:
Yarn writes its dependencies to a file named
package.json, which sits in the root folder of your project, and stores the dependencies files into the
node_modules folder, just like npm if you used it in the past.
starts an interactive prompt that helps you quick start a project:
If you already have a
package.json file with the list of dependencies but the packages have not been installed yet, run
to start the installation process.
Installing a package into a project is done using
yarn add package-name
yarn global add package-name
yarn add --dev package-name
Equivalent to the
--save-devflag in npm
yarn remove package-name
When installing many dependencies, which in turn might have lots of dependencies, you install a number of packages, of which you don’t have any idea about the license they use.
Yarn provides a handy tool that prints the license of any dependency you have:
yarn licenses ls
and it can also generate a disclaimer automatically including all the licenses of the projects you use:
yarn licenses generate-disclaimer
Do you ever check the
node_modules folder and wonder why a specific package was installed?
yarn why tells you:
yarn why package-name
If you want to upgrade a single package, run
yarn upgrade package-name
To upgrade all your packages, run
But this command can sometimes lead to problems, because you’re blindly upgrading all the dependencies without worrying about major version changes.
Yarn has a great tool to selectively update packages in your project, which is a huge help for this scenario:
At the time of writing there is no auto-update command.
If you used
brew to install it, like suggested above, use:
brew upgrade yarn
If instead you installed using npm, use:
npm uninstall yarn -g npm install yarn -g