• Updating a single dependency with npm also updates many unrelated ones based on semantic versioning rules.
• Yarn is a new package manager that replaces the existing workflow for the npm client or other package managers while remaining compatible with the npm registry.
• Many of our projects at Facebook, like React, depend on code in the npm registry.
• Throughout the entire process, Yarn imposes strict guarantees around package installation.
• The most popular JavaScript package manager is the npm client, which provides access to more than 300,000 packages in the npm registry.

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