As a JavaScript hater, I admit they surely they do, but I'm still curious as to why it was the best choice. If it's a custom runtime, existing runtimes being reliable\secure\well understood by existing engineers isn't relevant. And it's not like they're adding in lots of external libraries either.

I found this comment: https://news.ycombinator.com/item?id=19739454

" The language itself wasn’t so important as having adequate performance, robustness, memory use, reproducibility and extreme QC"

but I still don't understand. Interesting they went with a language that doesn't even have integers.

At least the comments on this reddit thread have some hilarious jokes:

https://old.reddit.com/r/javascript/comments/wrtny3/the_jame...

Looks like they released a paper, the abstract of which, indicates it's not a fully custom runtime, which would make more sense:

https://ui.adsabs.harvard.edu/abs/2006SPIE.6274E..0AB/abstra...

Unfortunately they want money to read the rest of it and I'm curious but not that curious, and I probably wouldn't understand it anyway.