Looks cool. If anyone is interested in a simple option with autocomplete working out of the box and no extra bells and whistles, feel free to check out my project: https://github.com/gutenye/script.js
For those who may be interested: I’ve built a project called Guten Email Notification, based on Cloudflare Email Service. It provides a simple way to send notifications to yourself from NAS, homelab servers, or GitHub Actions. You can check it out here: https://github.com/gutenye/email-notification
I guess, you might have enabled "Facebook Container" add-on while browsing this site. It is very restrictive in terms of blocking content that comes from Facebook Inc. addresses.
But both Flow and Jest are both developed by the Facebook team. First of all, like the author, I didn't say Flow is bad than TypeScript. Secondly, I moved from Flow to TypeScript last year. Anyway, this going to have a huge impact on Flow ecosystem.
FB devs show that there are no dogmas, only different solutions to different problems. Flow has its merits and was a good start as an experiment back then.