This looks like copy pasta, I swear I've seen this before.

EDIT: I see

Typescript docs are good [0], and it's incredibly easy to pick up, since it's just javascript with type annotations.

[0]: https://www.typescriptlang.org/docs/

Maybe take a step back and look at foundational topics such as higher order programming. Then you can take this foundational knowledge and apply and use it in any programming language and not be surprised when you come across it.

The ternary operator is born out of the need for an expression form of if-else. Some languages have if-else already implemented as an expression so they don't need a ternary operator.

Typescript exists to provide a static-typing discipline to javascript, if you don't care about this obviously you won't see the importance of typescript.