Class is a bit of a shambles. Yeah, it does make it easier to create constructors. But it also papers over the underlying prototype inheritance structure and can mislead beginners into assuming there is class system in place.
The fat arrow notation and destructuring are part of my everyday code lexicon, promises are hawt, im genuinely excited you can cancel a fetch() now, but so many other thing (proxies ffs) feel like they haven't added anything meaningful.
Which isn't to say I dislike the sugar, I have a hella sweet tooth, it's just that ES8 feels like it contains perhaps a little too much abstraction.
As recently as September the AbortSignal approach was implemented in Edge 16 and Firefox 57!
Pertinent piece from prominent professional Promise proponent Jake 'i don't only write about bloody promises' Archibald...
https://developers.google.com/web/updates/2017/09/abortable-...