None of the available alternatives to typescript — Elm, Purescript, Reason/Rescript — give me the same feeling of confidence in the future direction of these projects as typescript does. At least typescript is very closely aligned with the development of javascript; and it's also very widely used.
- Elm: not general-purpose enough (only useful for UIs), plus has a tendency of making drastic changes between versions (remember how loudly people complained here? [0])
- Purescript: the designer of the language, Phil Freeman, has stepped away from this project, and it doesn't seem to have gained sufficient traction
- Rescript: I'm put off by its ocamlness; and worry whether it will repeat the trajectory of Flow, which has essentially become irrelevant