How do I edit project files?

is there a way to edit project files within the project?

For context, I want to be able use in .txt files in the project to allow the user to save/load word sets in.

To do this i want to use the ajax plugin to read project files and use the string contained in those files to fill some variables.

Is there a way to tell the program to load in a text file to read from or does the .txt have to be a project file to be used with AJAX.

tl;dr

How can i allow the user to edit project files (.txt)?

Thanks

All advice appreciated