Child objects within modules

I wondering the best way to handle this, and the best way to set modules up for child and parent relationships.

Using a filesystem as an example, say we have 
var myfs=require('FileSystem');

var file=myfs.createFile('test.txt');
file.write( 'data');
file.close();

Do we have a single module that contains both the FileSystem and File objects?

I want file to have a reference to it's parent, and have it's own methods.

Should this be set up as two modules, where Filesystem is a list of File objects?

I've not seen any modules that contain two or related classes.