TiddlyIO is JavaScript library to access files on the local system. As one might already have thought by the name, it is based on the functions TiddlyWiki uses for its saving mechanism. For now, it is basically just some copy&paste stuff, but I'm pretty sure I will add some stuff to it as time goes on.
See http://www.tiddlywiki.com/
TiddlyIO is licensed under the MIT License. For more information, see the LICENSE.markdown file.