This is likely referring to TypeScript.

TypeScript has all of these patterns, they are used very frequently and they are necessary because TypeScript tends to be interesting from time to time since its types only exist at compile time, because it compiles to JavaScript, which is a language without types.

TypeScript also allows any as a keyword, which says “I don’t know which type this is and I don’t care”, which still produces valid JavaScript. To get back to typed variables it is necessary to use typeof (or similar constructs like a type guard).

https://www.typescriptlang.org/docs/handbook/2/typeof-types.html

I have my own mailserver just for me and it wasn’t that complicated to be honest. I set it up with Mailcow in Docker in under a day. So far it has been stable with regular backups and updates through Lighthouse.

Maintenance comes down to 5 minutes every three months because somehow Let’s Encrypt and Mailcow don’t like each other and I have to renew the certificate manually.