Comments – autosaving or saving as draft?

Hello

Is it possible to ‘save’ comments in WP. Ideally, some kind of draft or autosave function for registered users.
Or at least a warning that you are leaving the page if you accidently close the browser page before posting your comment. This would useful when making a lengthy comment and not losing your text.

I’ve done quite a bit of searching but with no luck.

thanks