I don't know if the billon dollar one will have that feature but this one does has solutions for that. If you click on preview, what you have written is saved, and if you accidentally click on the back arrow, then click on the forward arrow and the text is as it is.
Crucial part of this is "if", and preview is not really a solution for this problem as sometimes you will simply forget to press it and unless I am mistaken, few times it didn't even work.
Yeah, if you clicked back arrow accidentally, then you have to click forward and your text is saved.
For some reason that doesn't work for me 100% of the time and I never figured out why. By the way, I am using Mozilla.