I faced this issue on Ask Ubuntu long time ago, and it was gone. But for the two months, I'm facing this issue on every SE website I'm visiting.
I'm using Fedora 27 GNOME, Firefox Quantum, and I also have Chrome, latest updates. For the last two months almost, every time I post a comment, I have to refresh so I can see my comment. Even if I edit my comment, it will disappear, and I have to refresh again.
Error: Permission denied to access property "apply" [Learn More] jquery.min.js:3:11594 trigger https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:3:11594 trigger/< https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:3:18983 each https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:2:2879 each https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:2:844 trigger https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:3:18962 n.fn[b] https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:4:16315 submitNewComment/< https://meta.stackexchange.com/content/Js/full.en.js:5:3669 i https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:2:27444 fireWith https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:2:28213 y https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:4:22719 c https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js:4:26925
I've caught the bug; it's caused by the plugin uGet:
I am not sure if you can do anything about it. I'll notify the creator of the plugin. When I disable it, everything is fine.
Please note that this plugin might be the only plugin that works with Firefox Quantum to open an external download manager. As FlashGot died, many users might switch to this plugin, so this bug might affect a large number of people, at least those using Quantum.