Yes, but it's also correct to say that he wrote a compiler. He is taking the assembly code you type in and translating it to machine code, then he's translatin

Yes, but it's also correct to say that he wrote a compiler. He is taking the assembly code you type in and translating it to machine code, then he's translating the machine code to JavaScript source, then executing that source directly. Translating a program from one language to another is compilation, by definition. While the first translation step could also be considered assembling, the second cannot.