[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.