With the right kind of cross-compiler I believe that C# and shim libraries are a near-ideal way to handle javascript development...

You've got a strongly typed OOP langauge on top that is also pleasantly dynamic and anonymous when it wants to be, available through one of the best IDEs on the market, and it can compile to javascript that is remarkably similar to the original source. You preserve the well-optimized JS runtime for execution, but preserve a primo development experience that eliminates a lot of the pain of larger JS code-bases.

IMO "Typescript" should have just been a compiler variant for C# that was more scripting oriented with associated tooling.