>>9
Yes, probably, though presumably this would make setjmp/longjmp have to be special forms and not be available as library functions?
Well, obviously the idea is to write a translator from C to JS, not to somehow implement all the necessary functions to allow for untranslated C execution as if it were JS.
And if you were wondering about that other thing,
It is unspecified whether setjmp is a macro or an identifier declared with external linkage. If a macro definition is suppressed in order to access an actual function, or a program defines an external identifier with the name setjmp, the behavior is undefined.