I'd say don't type out anything you wouldn't want to send, not even as a joke. On multiple occasions I've seen people type a text or email as a joke, and then accidentally send it instead of erase it.

By that same token, don't send things you wouldn't want others to see (or perhaps, be aware of unintended audiences). How often do we hear about nudes being shared? In another example, I once worked at a company that had too many bosses, and one of them shit talked me to my boss in an email. They replied back and forth a bit, and then my boss had a question for me about the project they were now discussing, so he forwarded me the entire email chain. I saw exactly what the other boss said about me, and there was no denying he was the one who said it. I immediately and permanently lost all respect for him.

Yea, if someone on the internet got you heated just move on. It's not worth letting dumbasses online affect your mood.

Omg! I just had one of these earlier this week. Dumbass with a confirmation bias needs the size of Texas and a case of Dunning-Kruger that would make that one guy auditing a intro to "insert technical field" course that always knows the answer jealous. I am a degree holder in multiple integral fields to the topic, work adjacent to it and am a weekend researcher in the field and he was seriously trying to tell me that he didn't need to understand anything to tell me that his opinions were empirical fact that didn't need support. I tried to educate initially, but it became clear that all he was going to do was cherry-pick details out of context to support his opinion. I spent way too long. I just hope some other readers found the educational bits informational.

Ah yeah, great advice! I've also seen it expressed as "It's possible to have an unexpressed thought". I remind myself of that often!