TypeScript: Why you have to add types even if you handle the undefined case

I later came to understand why it was important to add types for it. Here's an explanation for why.

[wire_surfer]

You can do foo.bar! which explicitly tells ts compiler that bar is not undefined.

[gabriel_ts]

Why so secretive about reason behind learning TypeScript 🤔

[AlexNudelman]

There is no problem in JS. You are solving the problem that doesn't exist in JS

➞ node
>
> const foo = {}
> const bar = typeof foo.bar === 'string' ? foo.bar : 'history'
> console.log(bar.slice(0, 3))
his

[natqe]

The idea of types is good, but typescript is is too much strict
.