4 ways to use the TypeScript infer keyword

I've always been a little baffled by TypeScript's `infer` keyword? So I explored the ways you can use it, and came up with 4 variations! If you have other fun examples of how to use `infer`, let me know in the comments!
0:00 - Intro
0:32 - Generic Arguments
2:25 - Arrays
4:37 - Function Parameters and Return type
7:03 - Template Literals
9:53 - Outro

[@stonecoldcold2941]

I've always never understood infer. But the examples you have shown is the best that made me understand finally.

[@dimitargetsov9690]

Two reasons to remember and share this channel with anybody:
1.content (on TS) second to none.
2.family name -Burgess--same as of Antony Burgess--"Clockwork Orange".

[@andrew-burgess]

Lol thanks!

[@user-vp7ht2fg1u]

That is the best explanation of infer ever.
It is not fair.
Why shitty stuff like "BECOME A FRONTEND DEVELOPER IN 5 SECONDS" is much more popular...

[@serglohm]

Great job! This is definitely the best video about infer on 2022!

[@devinorium]

Upped the production quality. Looks dope

[@vihanv8582]

Wow! This has got to be the best video on the infer keyword I've ever seen. Keep up the good work Andrew! Liked and subbed 😀

[@BobbyBob21]

Thank you. Perfect examples.

[@user-zx8js8do5b]

What a great explanation, thank you so much!

[@AiguretDuren]

This was legitimately fun to code along with. Thank you!

[@i.j.5513]

Really nice demonstrations. Thanks a lot! It really made me understand the infer keyword better!

[@vishwajeetraj11]

This was Epix.
Looking out for more.

[@user-pk8dz4qc9b]

This was the best explanation for infer. Cheers!

[@ffedchik]

Awesome content. Keep up the great work!

[@the_proletariat]

This was cool. I didn't know anything about infer. Thanks to your video and challenges, now I know. Keep up the good work!

[@johnyepthomi892]

Dayum. This is very useful. Thanks for sharing.

[@joshreynolds4164]

Great explanation on this. Infer is so powerful

[@mohibwasay5102]

Wow. Awesome. Thanks Andrew.

[@developerfriendly]

superb tutorial!

[@gangster4208]

Thanks for the video!

[@kyuubyemy]

My implementation of FirstParam and SecondParam:
type FirstParameter any> = T extends (firstParam: infer A, ...args: any[]) => any ? A: never;
type SecondParam any> = T extends (firstParam: any, secondParam: infer A, ...args: any[]) => any ? A: never;
Also Jojo is everywhere LMAO

[@yujitomita3969]

Thank you for this. Agreed with Jimmy this is hard.

[@chamir4614]

Great video dude!! Thx you :D

[@mikedelcastillo]

you are a god kind sir, thank you!

[@ChesterRivas]

This is good stuff.

[@samirnayibruza9135]

You could do something like this instead of using overloads on functions:
```ts
interface Item {
id: number
}
interface FindOptions {
one: boolean
}
declare function find(options: Options): Options extends {one: infer FindOne} ? FindOne extends true ? Item: Item[] : never
const item = find({one: true}) // Item
const items = find({one: false}) // Item[]
```
Edit:
After a few minutes I realized that in the above case there is no need because I could just do `Options extends {one: true}` directly but imagine the possibilities 😁

[@edgarabgaryan8989]

awesome!

[@shayanpaul3430]

I have a question related to testing whether two types are equal or not. The utility type in @type-challenge is as follows :
export type Equals =
(() => T extends X ? 1 : 2) extends
(() => T extends Y ? 1 : 2) ? true : false;
Maybe it a very basic or idiotic question but i am unable to understand from where this T type parameter is coming from and what will be its values

[@andrew-burgess]

Definitely not a dumb question, TypeScript's syntax here is pretty confusing. My understand is that, by declaring a generic parameter T (that declaration is the part), you're saying that T should be assigned when you call the function. Like this:
declare function oneOrTwo(): T extends string ? 1 : 2;
const x = oneOrTwo(); // 1
const y = oneOrTwo(); // 2, because T defaults to unknown
I found this really in-depth explanation of the whole Equals type, which might be helpful too: stackoverflow.com/questions/68961864/how-does-the-equals-work-in-typescript
Thanks for watching!

[@georgejenkins4167]

Subbed!

[@MohamedRagab-kp6bp]

type MyParameters<
T extends (...args: any[]) => any,
I extends number
> = T extends (...args: infer A) => any ? A[I] : never;

[@michaelalls8230]

Tried to use typescript-challenges but getting an error on the import of the challenges utils. Is there something special that has to be done to get that working?

[@andrew-burgess]

Hmm, don’t think so. Can you comment with a link to your playground?

[@handsome_man69]

Handsome man

[@samislam2746]

omg, how do you know all that stuff!

[@afuzzybearsyoutubechannel2812]

💚

[@samirnayibruza9135]

🤯🤯🤯🤯🤯

[@JeanAlesiagain3]

Typescript has become very complicated

[@michaeldimmitt9974]

lol

[@alsbahsy]

this is harder than rocket science

[@andrew-burgess]

Nah, you got this! Let me know if you have questions, happy to help!

[@BHFJohnny]

Nope. Too advanced. Need to back off a bit

[@andrew-burgess]

Thanks for checking this out! Here’s one where I explain the details a little finely:
ruclips.net/video/wON6MCS0NkE/видео.html

[@AhmedAli-jx9ie]

I didn't understand shit

[@StuartLoria]

Weirdd explanation