ServerJS/Filesystem API

Prior Art

Microsoft Scripting.FileSystemObject. Used in classic ASP, WSH, HTAs.
JavaScript File object proposal (~1998)
Spidermonkey File object
Synchronet provides a File Class that was originally inspired by SpiderMonkey's jsfile.c, but has been widely used and enhanced over the years.
Ejscript's File class is still evolving, but is fairly comprehensive. It supports stackable streams such as BinaryStream, StringStream. It can also do I/O to and from a ByteArray class.
JSExt.File
jslibs jsio module
wxJavascript IO module
v8cgi has a File and Directory interfaces
helma has two File apis. One deprecated and one current
adobe's extendscript has a File constructor.Documentation is difficult to find online.
generic collection/document resource (java) api (work in process)
Opera Software's File I/O API for widgets, which will probably be standardized by the W3C Web API Working Group.

Summary/Comparison of current File APIs used by JS engines ServerJS File Object Survey