Comment by sharpercoder

The categories are subjective but at the same time driven by a plethora of factors. The fact that TypeScript is developed by a large company means that it can overcome many barriers. Another factor is that the same company develops a new IDE (editor) in tandem; this means one of the most important parts of a language (tooling) is covered. A third factor of TypeScript is the many language features it offers. Fourth, the development pace is very high compared to most other projects. The "innovation factor" of TypeScript is combined quite high, as the "compile-to-readable-js", language features and tooling support combination is not achieved by many competitors.

Flow is a nice comparison as it is also backed by a large company. They don't offer a developed IDE in tandem, development pace is a lot lower and language features are not that many compared to TypeScript. The "innovation factor" is a lot lower - of the level I think it's not worth pouring resources into it.