For our web app we've been sticking with JavaScript so far. It's a conservative choice with a lot of problems due primarily to the absence of typing. The absence of typechecking is a problem for our moderately complex app (> 10K lines).

Alternatives that we've been considering include js_of_ocaml and TypeScript.

For the kind of Android app we're developing we wanted a native look-and-feel. That means using the Android SDK, and I don't know how going through OCaml would make that any easier.