Junior JavaScript Interview - Part 2: Algorithm + Debrief

[@taintedbeats]

Shout out to Jay and Brooke's Developer Army! Great job, my friend!
The feedback given is absolutely invaluable. I'm taking some of your advice and putting that in my pocket to work on myself for future technical interviews. Thanks for doing this!

[@andrewwall2730]

Don't think hashmaps are necessary. Have you tried flatMap using new Set and then just loop checking if indexOf === lastIndexOf and push to array.