Mapped Types - Advanced TypeScript

In this video I'll explain how to create and use Mapped Types in TypeScript.

00:28 A simple example
02:59 Create a new type based on an existing object type literal (using keyof to get properties of a type)
05:14 Recreating the Pick type
07:19 Explaining how mapped type is used by Record type
09:05 Difference between an interface with an index signature and the Record type
11:12 How to add a specific property to a mapped type?

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[anuragrai]

This is the one of the best explanations regarding advanced typescript concepts No one likes you explain this on YouTube ever thanks a lot sir.

[mykyta-maria]

Чудове, послідовне пояснення!) Дякую!) Підписався на канал :)

[samelie]

Thank you for these! Great teacher and hacker! Understanding the composability of Typescript is key to writing less of it

[renisoncrawford]

Wow! Speechless... Your tutorial is a work of art that is crafted to perfection. Thank you for taking the time and sharing your talent with the world.

[pragmaticivan]

Keep it up! Pretty good content! Thanks for taking the time to record those videos!

[imsarvesh_]

Man your videos are on another level. Fews videos on this channel are so advance, that I need to watch several times..

[inaccessiblecardinal]

Excellent work. Ran into Records for exactly the limitation of [key: ?]. I don't have a lot of use cases for the generality of keys, so I worked around it and forgot that it bugged me! Thanks for the deeper dive.

[vaylinne]

Being pointed to useful typing declarations sure saves a lot of time compared to digging through the entire Typescript documentation, thanks :3

[YonathanBenitah]

I like how you are teaching. Very clear...
Thank you

[shahid]

You are very clear in your thoughts and so as conveying it to others. Great content with easy explanation. Thank you!

[borasumer]

Thanks mate, excellent tutorial. Instantly subscribed.

[TheAUa]

Nice and very good to understand. Finally I have the chance to get into TypeScript magic...

[SimonProductionsTM]

Thanks for the explanation. Great video overall :o.

[andreicristea]

Thank you Dimitrii. Only now I had on a project @ts-ignore statement and could overcome it with your Mapping Types Solution. Really it made the code look so nice and persistent now. Awesome!

[casual_sky]

Thank you for making this! I've learned so much. Can you please do a deep dive into Generics? What you can and can't do with them, interfaces with generic member functions and such? I'm really struggling getting things to work and I can't find videos going deep into them.

[maksym]

Дякую, Дмитре!
В кінці (12:09), через посилання на 2 інші відео зовсім не видно що коїться на екрані.

[SuperQuwertz]

Damn is this stuff useful. Great explanation!

[harshtiwari]

Is there any way we can do reverse of it …?

[mikhailkh]

Like, share, subscribe!
Awesome! Thanks for explanation!

[gerda-morozova]

Mapped Types - это всё ещё самая непонятная для меня тема. Я просто не понимаю как начать думать конвенцией Typescript, чтобы также жонглировать дженериками.
Вот например даже на видео есть запись вида <K extends keyof any, T>, но какие ключи могут быть у "any"? "Any" может же быть чем угодно, хоть числом, у числа нет ключей, но typescript почему то не ругается. Всё это только сбивает и сеет смуту в мою голову.

Или вот ещё пример. На видео 7:03 мы говорим, что "a" - это keyof "T", но "T" имеет в себе ещё и "b". Почему Typescript не ругается на отсутствие "b" - мне тоже неведомо. И в процессе я наблюдаю кучу таких вот вещей и нюансов. Надеюсь когда-нибудь я осознаю дух машины Тайпскрипта и посмотрю с недоразумением на прошлую версию самого себя.