With the v7.4 release, npm 4 became the bundled, default package manager for Node.js. In the meantime, Facebook released their own package manager solution, called Yarn.
https://blog.risingstack.com/yarn-vs-npm-node-js-package-managers/
origin - http://www.pipiscrew.com/?p=6419 yarn-vs-npm-the-state-of-node-js-package-managers