Facebook fixes several problems with npm; will yarn become the new standard, will npm make changes, or will developers not care?
We’ve used the npm client successfully at Facebook for years, but as the size of our codebase and the number of engineers grew, we ran into problems with consistency, security, and performance. After trying to solve for each issue as it came up, we set out to build a new solution to help us manage our dependencies more reliably. The product of that work is called Yarn—a fast, reliable, and secure alternative npm client.
Read more at Facebook Code