Mostly C because you need to type more C code to do the same with JavaScript, so I suppose most of the logics are using JavaScript. Plasma desktop has 2% JavaScript (invent.kde.org/plasma/plasma-desktop), it’s not comparable. 🙂
My current work forces me to work with Apple (because they are lazy to prepare Linux for working), I have been on Linux for almost 10 years and I really want to quit my Job because of this stupid Apple laptop, it is trash, the DE is stupid, and I have many issues (with settings, login items, alacritty not working… yabai stopped to work without any reason…) that stresses me a lot… So good, I love my work and I still enjoy working, but the macOS is pure trash.
Well, if you are new to Linux, it is better if you just install new distros to try them, I would go to Arch Linux as it’s the cleanest distro, I could install multiple DE without issues, but then it’s a bit mess of packages, also it’s harder to install, you need to type archinstall and understand their options. I have a desktop and laptop and I always use the laptop for testing, if you copy the ~/.config folder, you can restore all your applications settings (just copy the app settings you are using), ~/.mozilla to restore your browser as you had it before the wipe and some more settings are under ~/.local. I also copy my ~/.zshrc because I have a custom prompt, configs, add-ons, alias…
JavaScript isn’t the best language to make a desktop interface in my opinion, it can be very efficient, but you can see in bugs (at least in the past) how bad performance it had, and they needed to re-factor it to replace to C or improve the JavaScript. I’m just laughing and making fun of it using JavaScript, not saying it is slow, Gnome is pretty fast nowadays.
There is less than 4% more code in C than JavaScript. That’s pretty much, many features on the gnome-desktop is using JavaScript too, like gestures and mouse events.