You get a little closer with Fable to compile F# to JavaScript. It lets you model your domain using F# types (which are just as good as – if not better than – C# types) and then you can use them both from your C# backend and F# or JavaScript frontend (whichever you prefer.)

It does require you to faff about with toolchains for building frontend code though (WebPack and the like), and it's not always completely seamless, but if you want to invest in a shared domain model it's the most compatible I've been able to go at least.