Facebook recently released Yarn, a new Node.js package manager built on top of the npm registry, massively reducing install times and shipping a deterministic build out of the box. Determinism has always been a problem with npm, and solutions like npm shrinkwrap are not working well. This makes hard to use a npm-based system for multiple developers and on continuous integration. Also, npm slowness in case of complex package.json files causes long build times, representing a serious blocker when using Docker for local development.
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