Condensed version of This Post
Use Yarn in place of npm: Workflows don’t change; Packages load faster; Consistent node_module structure.
yarn init = npm init yarn install = npm install yarn add [package] = npm install [package] --save yarn add [package] --dev = npm install [package] --save-dev yarn remove [package] = npm uninstall [package]
Longer Version of This Post
npm is currently king of the Node package managers. Yarn is an alternative package manager that tries to fix what could be problems for some npm users. Yarn provides faster load times, dependency consistency and shorter commands, all within the same workflow you are used to with npm.
Installation and Use
If you already use npm, install Yarn with npm install yarn -g . That’s it! You can now use the yarn commands just like you would with npm. If you feel silly installing npm’s replacement with npm you can download an installer instead. Use your existing package.json file or create a new one with yarn init . Run yarn add [package] to install new package dependencies . Removing installed packages is as easy as yarn remove [package] . Install all of the dependencies of an existing project using yarn install,or even just yarn .
Deterministic Package Installs
Deterministic Package Installs is a fancy way of saying: The same module dependencies will be installed with the same structure on any machine using yarn. The structure of dependencies in the node_modules directory can be different from machine to machine when using npm. This can potentially cause a dependency to work on one machine but break on another.
Yarn installs packages faster than npm. Yarn starts by comparing a dependency against what’s already in the global yarn cache. If there’s no package cache, the package is downloaded and placed in cache. Once all dependencies are cached, yarn copies all necessary files only once to the project’s node_modules directory.
Downloaded and cached packages don’t need to be re-downloaded in the future. If you nuke your node_modules folder and run yarn install again, your dependencies will be copied from the cache into your new node_modules directory very quickly. If you start a new project somewhere else on the same machine, only dependencies that have never been used elsewhere are downloaded. The rest are pulled from the cache and merged with the downloaded ones. This makes for a very fast load.
Do you really need to use Yarn? Of course not. Lot’s of people use npm for their projects with little problem. But on projects where dependencies have to be installed separately among several users, module consistency could become a problem. Yarn solves this and provides other great enhancements to npm. Yarn provides a similar use experience to npm. It provides all the same packages, is faster and has simpler commands. It can even tell you why a package is being used. There are few if any downsides and you can always go back to npm.