It's the only implementation almost everybody knows of. I've never heard of any other, don't know if there is other. In defense of the author, he does explain

It's the only implementation almost everybody knows of. I've never heard of any other, don't know if there is other. In defense of the author, he does explain why it will most likely always be a language that will be implemented in a compile-to-js fashion. Do we check compiled code when we code in C? Do we look at the Bytecode when we write Java? This is exactly what he is complaining about. Also, he does makes a few points about CS syntax, that can't be the implementation's fault.