Yes, it took me a while to "realise" (or perhaps "accept") this as well. What is machine code? Code that a machine can execute natively? What if I built a machine that had primitive instructions for JavaScript? Then JavaScript would be machine code, and an X->JavaScript "transpiler" could be considered a "compiler".

Now what if before building such a machine, I wanted to simulate one? I could write a "virtual" machine, which is really just a program that acts like a physical machine with native JavaScript instructions. Also known as a JavaScript interpreter.