In SIX LINES of Code I Fixed Two Major NodeJS TypeScript Issues

The promisify utility in node has two major flaws in its type definitions. So let's fix them in six lines of code.

0:00 Intro
0:11 The issue
3:50 The solution
8:40 Try the solution
10:30 Outro

[alexeydmitrievich]

Builtin implementation was probably created before TS features making this possible existed. Cool video. Very fun to watch after dealing with C++ compile-time magic

[royz_]

This built in implementation reminds me of the package that checks for odd/even with millions of if checks 😂

[ryanvarley]

Mate, I’m learning so much from watching you work with types! Thank you!

[caineandrebekah]

We need this in the @types/node package now!

[supravatsamanta]

These are the kinds of things for which I'm paying my internet bills.

[leogt]

Man, you're miles away from every other Typescript youtuber I see.
Great content, actual useful code, and great explanation. Nailed it!

[RobertMacLeanDeveloper]

I always learn something useful.... mostly how damn smart you are!

[AlexanderBrownDrJKL]

Have you tried the twoslash extension to have more persistently visible type information?

[feldinho]

Could you to the same to the pipe function from lodash? I’ve tried many times to tackle that but with no success. I’d love to see how it’s done.

[deathone]

I throw the argument out that if you have 6+ parameters then refactor. Is there a way to do this while still keeping just five or fewer?

[axeloord]

Watching this I have learned 2 things:
- I know nothing.
- The people creating nodeJS are the same as me.

[BeyuuKT]

I think GetResult and Callback not needed:

type Promisified<Fn extends Function> = Fn extends (
...args: [...infer Args, ((err?: any) => void) | ((err: any, result?: infer R) => void)]
) => void
? (...args: Args) => Promise<unknown extends R ? void : R>
: never;

[ayushtripathi]

Can you do a video on creating types for pipe function?

[ErrorNaN_]

Love this!

I wonder what the performance cost is of your approach compared to the size cost of Node’s explicit approach. 🤔

[amirulidzham]

I think you mean major instead of mayor

[vanilla_master]

All that remains is to add support for overloaded functions (it is not really that easy)

[snatvb]

interesting, can we use it with overloading, for example for autocarry functions :) when u have sum = (x, y, z) => x + y + z and u can call it like sum(5) -> (y, z) or sum(1, 2, 3) -> 6

[winchester]

Bro is on the way of creating sane STD for Node 💀

[PieterWigboldus]

NodeJS: what are you doing, you make it more complex with some overhead, it just works, why do you need the types, just read the docs and run it. 😉

[LePhenixGD]

Man the NodeJS implementation is so goofy