I think the reactive/rx/observer patter might be an acceptable solution around the what color is my function problem and it tends to be very popular with the functional programming wing of the JS community from what I’ve seen.

Never understood why the browser didn’t ship a full access to something like an EventEmitter. Since you can dispatch events on window document DOM elements etc seems like being able to subscribe to events in a more arbitrary fashion that worked in parallel to the other events would have been useful and solved callback hell all the same