Why do we need Yarn?
NPM becomes part of developer’s life. Developers use it for both frontend and backend dependency management. Even though NPM is great, developers had lot of issues with it. Some of the problems are:
As you know, all packages will be stored
node_modulesdirectory in npm. If you’ve deleted your node_modules folder for any reason and run
npm installin the project console, npm will re-download each and every package along with their dependencies, which in itself is not required and takes up too much of your time.
NPM always installs each dependency one after the other which might end up using a lot of time. I used to take small walk after running
npm install:). Why can’t npm client parallelize the downloads?
There is no offline installation from my local cache.
Yarn is built to solve three main problems:
2 to 7x faster than npm
Yarn’s good performance comes out because of a interesting cache implementation. Whenever yarn installs a package, it caches it. So any time yarn sees a request for an installation for a package, it will first try to install it from its cache which makes it much faster. Also yarn, being a tool that is of this new age of concurrent coding, executes downloads in parallel threads to make the best use of resource utilization.
Anytime a package is installed and is about to be executed, it verifies the integrity of the package by using the package’s checksum. The same checksum method is used to also check if the caching process of the package was indeed successful or not. When it detects an incorrect checksum, the packages is again re-fetched from the original source.
Using a detailed, but concise lockfile format, and a deterministic algorithm for installs, Yarn is able to guarantee that an install that worked on one system will work exactly the same way on any other system.
When you run
yarn(equivalent to running
npm install), it creates
yarn.lock. This file is equivalent to npm’s Shrinkwrap file. But Shrinkwrap aren’t generated by default and will fall out of sync if engineers forget to generate them. To solve it, even after every upgrade or removal, yarn updates a yarn.lock file. So
yarn.lock file always keeps track of the exact package version installed in node_modules directory. I would recommend you to add this file to version control since it gives the package version consistency across all environments.
Yarn creates a cached copy which facilitates offline package installs. Therefore you can install your npm packages without an internet connection with Yarn. This is especially useful for Continuous Integration(CI) systems; they no longer rely on an internet connection and the npm registry, and your tests will pass even when npm goes down.
Overall, yarn offers a better workflow than npm.
You can install yarn through NPM
npm install -g yarn
You can update to the latest version of Yarn
The yarn CLI replaces npm in your development workflow, either with a matching command or a new, similar command:
How to Yarn?
For most of the command, yarn works exactly the same way like npm. But there are some changes in few basic commands.
npm install → yarn
With no arguments, the yarn command will read your package.json, fetch packages from the npm registry,
and populate your node_modules folder. Also it generates
Yarn simplifies the npm’s install and update command:
npm install react --save → yarn add react npm uninstall react --save → yarn remove react npm install react --save-dev → yarn add react --dev npm update --save → yarn upgrade npm install react --global → yarn global add react
For following commands, if you know NPM, you’re already set!
npm init → yarn init npm link → yarn link npm outdated → yarn outdated npm publish → yarn publish npm run → yarn run npm cache clean → yarn cache clean npm login → yarn login npm logout → yarn logout npm test → yarn test
As always, use global flag with care.
More ever Yarn has some great features that NPM doesn’t have. You can check the licenses of your dependencies and you can also generate your license dependencies.
yarn licenses yarn licenses generate
Oliver Combe added a great tool
yarn why package-name, this will identify why this package is installed and
which other packages are dependent on it.
yarn why react
As far as I played with yarn, it looks amazing and I did not find any issues. Since the project is backed by companies like Google and Facebook, I am optimistic that it can become the official npm package manager soon.
Great work by the Yarn team for such a wonderful tool. I’m looking forward for much more improvement in the future.