I think I would be good. They are using the ace text editor, so something simple like:

on pageload: var t = localStorage.getItem("textbackup"); if (t){ __editor.setValue(t); console.log('restoring from backup'); } else { __editor.setValue(document.getElementById('basic_intro').innerHTML); console.log('putting in the intro'); }

and on any action: var text = __editor.getValue(); localStorage.setItem('textbackup', text);

It's the approach I've taken in my version a playground for a different program. http://xqt2.com/mjslab/mjslab.html

That's definitely useful, but the current Rust playground already does this (sorry for not being clear in my post). I meant a more full-featured history where you can view multiple previous edits, not just restore the last one.

It would be great if this could also show diffs to previous versions!