I took a peek at the "Explorer" app code base. PHP + JS + jQuery, but surprisingly readable (but a lot of practices in there that are not exactly considered "best" today). Perhaps we have sunk too deep into the SPA/API rabbit hole that we can no longer appreciate simplicity.
https://gitlab.com/hsleisink/orb/-/blob/master/public/apps/e...
https://gitlab.com/hsleisink/orb/-/blob/master/public/apps/e...