Notes Class Static Fields (Public & Private): 3 to 2. Class fields and private methods will be merged, and split. Class instance fields (public and private), and private instance methods are now one proposal, and at Stage 3. Class static fields (public and private), and private static methods are now a second proposal, and at Stage 2. – https://github.com/babel/proposals/issues/34#issuecomment-348

Statement Brian Terlson who is editor of ECMAScript said that Speaking as someone who proposed types for JavaScript in 2014: I do not believe types are in the cards for the near future. This is an extremely complex problem to get right from a standards perspective. Just adopting TypeScript as the standard would of course be great for TypeScript users, but there are other typed JS supersets with pr