[nine_k]

Certainly so! The first example is needlessly contrived.

But instead of

  for (const i=0; i < data.length; i++) {
    new_data[i] = old_data[i].toUpperCase();
  }

you can write

  const new_data = old_data.map((x) => x.toUpperCase());

I think it's both more clear and less error-prone.

[nuancebydefault]

The second code does not compile and introduces a new dependency.

[nine_k]

Sorry, are we speaking about the same language?

https://www.typescriptlang.org/play/?#code/MYewdgzgLgBCA2ATA...

[nuancebydefault]

My apologies, I thought it was C++. I should learn typescript, it is one of those I'm postponing.

[Izkata]

Nothing in that snippet is Typescript-specific, it's just plain Javascript.

All syntactically valid Javascript is also syntactically valid Typescript, it just adds stuff, though you can get runtime errors for things like reassigning variables in a way Javascript is fine with that Typescript disallows.