"We're thrilled with the adoption and community engagement," Facebook's Yarn team commented in a blog post announcement. "Yarn's main focus when we launched almost a year ago was stability, resiliency, and performance. Building on the core principles of what made yarn successful in the first place, the 1.0 release comes with many new features that we hope will help the Yarn community move faster and build great projects."
The main attraction to Yarn has been dramatically increased install times, performance improvements, and better stability. With the likes of Twitter, Microsoft, Outlook.com, Expo, Kenzan, and Sentry joining the Yarn bandwagon before the launch of 1.0, the project is certainly on the right track.
New features in Yarn 1.0 include Yarn Workspaces, auto-merging of LockFiles, and selective version resolutions. Yarn Workspaces allow users to install dependencies from multiple package.json files in subfolders of a single root package.json file, all in one (in short, users can easily transition code into a mono-repository to ensure the latest code is always used). Auto-merging ensures that contributors are always pulling the latest code which avoids conflicts when building in a team. Selective version resolutions streamlines version control (i.e. the feature ensures that the code being used is updated with the most recent security parameters and bug fixes).
Yarn 1.0 also includes a number of fixes and other improvements. For a full picture, check out the changelog. The team is quick to praise the very active Yarn community that has led to massive adoption of the open source project (almost 3 billion package downloads each month). For those interested in learning more, get engaged with the community and/or start contributing.