> In this particular case, Ruby is not being compiled to JavaScript but being transpired.

First, "transpiled" not "transpired".

Second, "transpiled" is a special case of "compiled", so you can never correctly say that something is not being compiled but is being transpiled, in the same way you can't say something is not a rectangle but is a square.

it's a mix, some stuff is high level (closure), some is low level (for loop before ECMA6). This is very uncomfortable when you're learning it, you never know on which side you are.