Fades or completely hides the less important "Like" and "also commented on" notifications that clutter your Facebook Notifications dropdown list, so you can focus on the ones that matter: 1) comments on YOUR posts; 2) replies to YOUR comments on other people's posts; and 3) comments from the AUTHORS of other posts you have commented on.

Pretty critical for anyone who posts/comments a lot on facebook. Kind of ridiculous that this isn't a built-in feature for power users, but anyway.

(This is adapted from http://freestyler.ws/style/131099/fade-or-hide-likes-in-facebook-notifications to support hiding Reactions and other new types. Default settings are as I use them, but the code is pretty well-commented and you should be able to adjust it as you go.)