> Here's what I don't understand: why is there any focus on alternative VMs for specific languages? Surely all this effort should be going into a VM for some kind of highish-level intermediate representation that's trivial to generate from any source language? That way no language has a monopoly and there can be peace on Earth.

I've always wondered: why not LLVM? It's low-level, so the speed is there, and I think should be trivial to compile as it arrives at the browser. Tons of stuff already compiles to it. You can compile it to JS. Of course, you'd need to make sure it doesn't make a syscall that's not allowed (and I'm not sure how hard that is), and that it has bindings into JS APIs and/or the DOM, but aside from that…

I'm sure some people will suggest things like the JVM or the .Net CLR, but I feel like those have certain qualities (e.g., GC) that don't appeal to all languages.