Re: Biggest problem is the name.
> File I/O in Javascript?
You are aware of course that the C specification¹ does not cover file I/O?
> If these (apparently) simple tasks are buried deep in the manual
I am not quite sure you understand how language specifications² work, or the difference between specification and implementation.
¹ The standard library does, but you can write a fully compliant C implementation without any file I/O functionality.
² For languages that do have one, such as so-called JavaScript.