In 2018, I came across TypeScript which—while much less fun to write than CoffeeScript—was far more widespread, used professionally, and promoted better coding practices, prompting me to switch. Since I was already using Node/Gulp in my CoffeeScript workflow, transitioning to TypeScript wasn't a large step.
Unfortunately, documentation for userscripts is sparse and outdated at best, so I've been forced to develop my own custom workflows and create atypical solutions to problems that could otherwise be easily-solved with access to the source code. As I plan on developing many more userscripts in the future, I created a Typescript Userscript Builder that allows a userscript project to be set up quickly and painlessly. It includes TypeScript & Sass, automatic timestamping/version incrementing, build/watch/release commands, easy metadata configuration, and other helpful features.
The first and largest userscripting project I've undertaken is a complex script for a small, private hobby community. The script—which is used by many dozens of people—inserts its own settings page, adds buttons, tweaks layouts, filters messages, and fixes small bugs. An example based off an earlier version of the script (compiled from CoffeeScript) is linked below. I've also contributed to some scripts that link books/movies on database sites to others, or created scripts simply for my own day-to-day use.
The userscripts are tested in Chrome & Firefox using both Tampermonkey and Violentmonkey, but will likely work in any modern web browser since ES6 support is now commonplace. The scripts are loaded into Violentmonkey in Chrome during development to take advantage of how Violentmonkey auto-refreshes the script as changes are made.Userscript Builder Demo Script