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TypeScript - get types from data using typeof

Andreas Bergqvist on April 10, 2019

A great way to make sure the values you set to your variables matches what you would expect is to set specific types to them. If you already have ...
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Andy Perlitch •

Thanks for the post. Is there documentation on that typeof myConst[number] syntax? Specifically the [number] part is something i've never seen in typescript, and can't find on the doc site.

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Eugene Karataev • • Edited

New TS Handbook has a mention about [number] syntax:

const MyArray = [
    { name: "Alice", age: 15 },
    { name: "Bob", age: 23 },
    { name: "Eve", age: 38 }
];
type T = (typeof MyArray)[number];
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Andreas Bergqvist •

Hi, I'm not sure. Been a while since I wrote this and its a gathering of things I read and things I just tested with code...

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sol •

It was very educational. Thx for the post.

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Cubicle Buddha •

Wow!

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Rinat Safin • • Edited

Very big thanks!
Can you add how to create a type by type/interface (like object) values in typescript?
drive.google.com/file/d/1B-Jv-1VOK...

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J.D Nicholls •

You're my friend!

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Riva Yudha •

A helpful cheat sheet. Thanks!