Let's prototype a JavaScript JIT compiler [video]

This video was fascinating; I consider myself a competent engineer but I was totally humbled by watching Andreas build this prototype from scratch.

The Copilot interaction by itself was just mind-blowing; I have Copilot set up as well but it's nowhere as "smart" on my code bases (I discard 90% of the garbage it generates for me, so I guess I need to dig into that some more and figure out what I'm doing wrong).