I use Processing 3.5.4 in python mode. I’ve been unable to find a setting for autosaving files. Almost every week I lose some work to this. I can’t believe there is no autosave available, yet I cannot find a setting, and web searches mostly yield old, old forums posts, etc.
What is the current 2020, modern Processing 3 answer for autosaving?
https://processing.org/reference/save_.html A line in your code could be used. Otherwise you’re just going to have to remember to save.
I’m saying I want to auto-save the source code of my processing scripts, not an image output from that. This is a common element of every UI of the last 25 years. I can’t imagine why it doesn’t exist in Processing.
You could use a different code editor – Atom, Sublime, or any other editor with an auto-save setting – coupled with the command line version of processing.py configured to run your sketches.
Hoping when Processing 4 hits they update the PDE and add this feature …
for now if you loose a sketch you can try to find it in the temp folder. When focused on the PDE hit ctrl-k, go up two folders to temp, find the newest folder matching the name of your sketch, should be a .java file inside. Not the best experience but atm I think its the only hope one has who forgets to save often.
I’m not that sure “Python Mode” leaves “.java” files there like “Java Mode”. 
Sorry, yes I meant %TEMP% ... C:\Users\System\AppData\Local\Temp`
and, my bad … did not realize it was for .py