Any recommended vids?
https://www.youtube.com/watch?v=hVfQ8KtRptM
And "Grokking Asynchronous Work in Node.js" which talks about async_hooks API is a good follow-up:
https://www.youtube.com/watch?v=vkgnSeGO_W0&list=PL0CdgOSSGl...
Fascinating what you can do with vision recognition and augmented reality on your phone.
I haven't written a callback API in quite some time.