Can we keep that onmousewheel handler in case we need it in older browsers?

I think the only difference between what @dfcreative has here and what we had before is that now we always attach to either wheel or mousewheel, whereas before we could potentially attach to neither if the browser doesn't support either one (I had to play with this - you may already know this but what's going on is if the browser supports wheel, then element.onwheel = null before any handler is attached, not undefined). And even if there is a case where the browser really doesn't support either, there shouldn't be any problem attaching to a nonexistent event.

Oh I see. My bad. 👌

Unfortunately, this might break older browsers, see:

https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#Safely_detecting_option_support

I couldn't find a list of which older browsers does not support {passive: true|false}, but we should probably play it safe here.

Good catch @etpinard - do we need a has-passive ala https://github.com/dfcreative/has-hover? Or even better, a module that would figure this out once and then export the correct 3rd arg to mark the listener active or passive:

var eventOpts = require('event-opts');
element.addEventListener(wheelEventName, handler, eventOpts.active); // false or {passive: false}
element.addEventListener(wheelEventName, handler, eventOpts.passive); // false or {passive: true}

There is a polyfill default-passive-events for that. We could use detection logic from there in a way @alexcjohnson suggests.

@etpinard @alexcjohnson a32a21a introduces eventListenerOptionsSupported method to detect proper way to attach events.
To make code cleaner it is possible to introduce an event binding function or use package, like emmy or similar.