C : C++, Java : Scala/Kotlin, JS : TypeScript. There definitely seems to be space for languages that target the same platform.
AFAICS the success criteria are: great interoperability, similar toolset, similar syntax, and a more elaborate type system.
Are there counterexamples?
Scala.js looks exciting. It's rare to see compiled-to-JS langs with non-JS semantics but still allow interoperability with jQuery et al.