[throw49sjwo1]

Doesn't matter, I'm talking about the type definitions - @types/react, @types/react-dom and @types/express.

[authorfly]

No, those are optional for the enduser to ever encounter.

[throw49sjwo1]

I never said it's required. The typings are really useful if you want to use these libraries "with TypeScript" as I said in my first comment... The typings are the whole point - that's where the advanced type features are used, and every user benefits - their own code can be much simpler and safer thanks to it.