Greasy Fork is available in English.
arrive.js provides events to watch for DOM elements creation and removal. It makes use of Mutation Observers internally.
I'm aware of today's new version. I had set it to automatically update but unfortunately that didn't work (nor updating manually) because of old uploads by others (see Jason's reply here). That's why I posted the new version here: arrive.js 2.5.1 following Jason's comment.
Thanks
PLease update!
https://raw.githubusercontent.com/uzairfarooq/arrive/master/minified/arrive.min.js