At #io19, @_gsathya and I gave a talk on cutting-edge JavaScript features: https://www.youtube.com/watch?v=c0oy0vQKEZE …
WeakRef
Intl.*
Promise.{allSettled,any}
numeric separators
Array#{flat,flatMap}
Object.fromEntries
String#matchAll
…and more!
Just watched it this morning, there's some great information in there. Made me realise I'd wrongly assumed that Promise.all() would wait until all promises resolved or rejected. Looks like I need Promise.allSettled() instead 
