[kevingadd]

It's my understanding that Shumway is basically a full-scale AS2/AS3 VM & JIT using JS as the codegen target, is that wrong?

JSIL is increasingly a JIT that targets JS instead of an offline JS compiler, if only because JS runtimes are so terrible at optimizing C# code and semantics. Eventually it may end up being like Dalvik, where the offline compiler runs a filtering/transform pass on the input bytecode and all the actual codegen happens on the client.

Hard to be sure, as you pointed out it's hard to do serious CS research like this as one person in your spare time :-)

[azakai]

Thanks! I forgot Shumway. Last I heard it was competitive with the Flash runtime (better on some stuff, worse on others), so that seems like a clear counterexample to mraleph's concern.

[mraleph]

Isn't Shumway more of a confirmation for my concern than a counter example? Shumway is running ActionScript which is extremely close to JavaScript semantically though somewhat more strict and allows for optional typing.

[azakai]

It agrees on numeric types, but it has very large differences like namespaces, classes, etc. Look at how complex the Shumway VM is.

[kevingadd]

AS3 also has things like pointers (via domain memory). The closest thing to that in current JS is asm.js.