Conditional Types - Advanced TypeScript

[@billmcbungabine9404]

I've been searching for more advanced lessons covering typescript for a while and these are by far the best i've found and they are explained very well especially considering by the sounds of it English is not your native language - well done hope you release more content like this

[@DmytroDanylov]

Thank you

[@tigrankhachaturian8983]

Just read the docs, lol. They work most of the time, though, rarely I have to search external resources about a certain topic that typescript docs fail to explain to me and then return to docs to get a more advanced knowledge.

[@tigrankhachaturian8983]

Oh, I just spotted myself in the comments 4 months later rewatching the same tutorial, nice

[@burnCS]

One of the best tutorials about conditional types. Can't wait for more videos :)

[@pjeet4411]

This is great tutorial on advanced Typescript. I had pause in every 10mins to understand different type of format the extends take like type comparison, function comparison and tuple comparison.

[@bradyfractal6653]

Your channel is a gold mine!! You’re a very talented teacher 💙

[@dawid_dahl]

Thanks so much for providing more advanced TS content for free.

[@v23452]

Hi, Dmytro! Thanks for sharing the knowledge on a more advanced topic.

[@v23452]

May I ask your advice as to where I could possibly find a community of developers helping with TypeScript problems. Is there a Discord room or Slack channel or any other chat to ask questions and get quick answers?

[@孙凌峰-w7b]

15:04 what is different between 'type StringNot = T extends 'a'|'b' ? T :never' and 'type MyStringNot = [T] extends ['a'|'b'] ? T :never' . I still don't understand .

[@abrahamjones3635]

It became non-distributive when using [ ] brackets, unlike the first example which was distributive. When the type is not-distributive it means that the whole union type will be compared to the whole of the other union type as if both types were one big type. If the type is distributive (first example), then each type in the generic will be compared to each type to see if it exists in the union. So in the first example if T was 'a'|'b|'c'' then StringNot would result in 'a'|'b' because 'a' and 'b' are both in 'a'|'b', in the second example if T was 'a'|'b'|'c' , then MyStringNot would result in never because 'a'|'b'|'c' does not equal 'a'|'b'. In the second example if T was 'a' then MyStringNot would be 'a' because all the values for T are possible values in MyStringNot. To simplify, if a conditional type is not distributive it will return false if the one of the unions has a type that is not present I the other, else it will return true and all matching values will be returned in the type. Hope this helps!

[@nazaka9904]

Дякую за туторіал. Добре описана теорія, але хотілося б більше прикладів прикладного використання

[@drago8701]

Thanks for the clear explanation

[@laniquo]

This was very helpful. Thank you!

[@ikrammissaoui2272]

Amazing !

[@RachidBoukotos]

thank you very much, it's really informative

[@sunstrike8943]

More about typescript please

[@hirisraharjo]

Great video! Subscribed!

[@santosharakere]

Excellent demo, thanks.

[@jacinyan3893]

Just started learning TS, and I have been confused about the ‘extends’ keyword in here with say, interface/classes. Now it is kinda explained

[@codewithnws3544]

hey can you please create the video for infer?

[@harini3191]

Can u make more videos on typescript like this? , thanks

[@darkknight500]

Wow! Amazing tutorial ❤ . Thanks for sharing your understanding it greatly appreciated.

[@aditya.ishan27]

Loved it..

[@bakaleisanich]

Будут ли курсы по базовому тайпскрипт?

[@DmytroDanylov]

На сегодняшний день, у меня есть платный курс на Udemy по использованию TypeScript в React, в который входит модуль по базовому TypeScript. Вот ссылка: www.udemy.com/course/react-with-typescript/?referralCode=1816455EA4C12F9CA9F4 Пока что записывать видео для канала исключительно по базовому TypeScript не планирую, но будут видео, в которые входит использование TypeScript. Спасибо за вопрос.

[@sourishdutta9600]

You are too good :) make more videos like this

[@dimitargetsov9690]

Dear Sir, at 22.44: type ReturnTypeany>=T extends(...args:any)=>infer R?R:any; should be,IMAO, : type ReturnType=T extends(...args:any)=>infer R?R:any; Do You need (and why) to write that generic type T any> in the parameter list of ReturnType? Best regards.

[@Boris1990ua]

Good stuff, but what about practical use chases?

[@DmytroDanylov]

Thanks, conditional types are quite frequently used. You can look into the type definitions of your favourite libraries and most probably you’ll find some advanced examples for solving a particular typing problem. I think most recently I’ve seen conditional types in react-hook-form.

[@akitmentorconsultant4696]

Thanks a lot 👍

[@abdremo]

Thanks

[@ankitshukla185]

I have an interface defined as interface Xyz { abc?: string; } I do not know what ?: means here. Can anyone help?

[@gabiold]

Probably you are already figured out, but for those who don't: The colon is just the separator between the type and the identifier, the question mark marks the member as optional. So a type that has an "abc" member and it is of type string it fulfills the interface. If it does not have a member "abc" at all, it also fulfills it. But, if you give a type which has a member "abc", but it is not of type string, it then does not fulfills the interface. It is useful if your function that receives the Xyz interface does not require abc to be supplied, for example because it can do some default action without it, but if it is, then it should be of a certain type.

[@amoshnin]

Spasibo

[@adiscivgin745]

Hi all, if someone may help I would appreciate it. I have this interface: export interface StorageModuleConfig { appName: string; perUser?: boolean; authPrefixKey?: string; } My task is to make authPrefixKey required only and only if user provide value for perUser property.

[@olga-angel]

Для чого робити відеоуроки англійською, коли їх і так океан... Робіть українською, своє українське море.