The difference between CoffeeScript and TypeScript was that CoffeeScript offered syntax that people preferred, whereas TypeScript provides write-time checking o

The difference between CoffeeScript and TypeScript was that CoffeeScript offered syntax that people preferred, whereas TypeScript provides write-time checking of errors. It is more similar to ESLint in that regard, and is better understood as a linter than as a separate language like CoffeeScript. Even if TS's type annotations would be added to the language (like it practically almost has been, through Babel supporting it), you'd still want to run a tool as you write it to actually check that those annotations are adhered to, rather than having your code crash on the user when they are not. TypeScript is that tool.