Since you all enjoyed talking about template literal types yesterday, let's do another one.

What have you used mapped types for in your app code?

type Mapped = { [K in keyof Obj]: T };

What do you use template literal types for in TS?

I'm talking types, like:

type Route = `/user/${string}`;

I'm having a mental block and can only think of routes.

🏪 Excited to announce XState Store!

→ Extremely simple API
→ Extremely small (< 1kb min/gzip)
→ XState-compatible (if you need the power)
→ Extra strong typing (inferred!)

npm i @xstate/store

It's one of those days. I'm absolutely stonking through work that felt really hard 2-3 weeks ago.

I hope you're having one of these days too. Feels great.

strict: true,
noUncheckedUndexedAccess: true,

...tend to be as strict as I go in a tsconfig.

Which rules am I missing out on?

Working on this again...

TS Wizards:

Is there any reason not to turn `esModuleInterop` on in your tsconfig.json?

Why hasn't it been made the default?

4/17 chapters to go... The book is coming together.

As of yesterday, it also has a name.

Feels like every few months I get a cascade of likes for reminding people this is a thing:

namespace NodeJS {
interface ProcessEnv {
MY_VAR: string;
}
}

So, here's an article - which also recommends t3-env as an awesome runtime solution.

totaltypescript.com/how-to-strongl…

TS 5.5 is poised to be one of the best of all time

`skipLibCheck` being off by default in TypeScript is utterly confounding:

🤷 You probably don't own the code being checked
🚨 Errors may be unresolvable due to tsconfig differences
🐌 Very expensive for type check performance

Do any other languages have something like this?