Scriptingランタイムライブラリ FileSystemObject
http://www.microsoft.com/japan/msdn/library/default.asp?url=/japan/msdn/library/ja/script56/html/jsobjFileSystem.asp
http://www.microsoft.com/japan/msdn/library/default.asp?url=/japan/msdn/library/ja/script56/html/jsobjFileSystem.asp
http://www.google.co.jp/search?hl=ja&q=JavaScript+FileSystemObject&btnG=Google+%E6%A4%9C%E7%B4%A2&lr=lang_ja