I need to create a single html where the person can input text in text fields, then click a button and save the file itself, so he wont lose changes. The idea is similiar to what wysiwyg does to html documents, but I need that to be implemented on the doc itself.
Where do I start from? I can't find anything like that on Google, perhaps I'm searching the wrong therms.
Need something that uses HTML + Javascript, no server side scripting.
I think most of these answers are incorrect. Using the FileSystem API, content is only saved to a sandboxed hidden folder, the user has no control as to where it is saved.
As suggested by Sean Vieira, using TiddlyWiki is a good solution.
However, if you want to customise it, you can make a Flash/JS bridge in which the Flash SWF saves the actual content.