Translate 1 file to ko - Typeof Type Operator.md

[bumkeyy]

e1eedfa

리뷰 부탁드려요~

[github-actions]

Thanks for the PR!

This section of the codebase is owned by @bumkeyy, @yeonjuan, @guyeol, and @dvlprsh - if they write a comment saying "LGTM" then it will be merged.

[github-actions]

Translation of Typeof Type Operator.md

---

title: Typeof Type Operator
layout: docs
permalink: /ko/docs/handbook/2/typeof-types.html

oneline: "Using the typeof operator in a type context."

typeof Type operator

In JavaScript, Expression contextually available typeof There is an operator.

// "string"을 출력합니다
console.log(typeof "Hello world");

TypeScript type You can infer the type of variable or property in the context. typeof Add an operator.

let s = "hello";
let n: typeof s;
//  ^?

It's not very useful for basic types, but it's with other type operators. typeofYou can use to conveniently represent many patterns.
For example, a predefined type: ReturnType<T> Let's take a look at it.
The above type Function type provides the type returned while receiving .

type Predicate = (x: unknown) => boolean;
type K = ReturnType<Predicate>;
//   ^?

In function name ReturnTypeWith , you can check for instructional errors.

// @errors: 2749
function f() {
  return { x: 10, y: 3 };
}
type P = ReturnType<f>;

value and type Keep in mind that is not the same.
value f of type To infer typeofUse .

function f() {
  return { x: 10, y: 3 };
}
type P = ReturnType<typeof f>;
//   ^?

restriction

TypeScript typeofIntentionally limits the kinds of expressions that can be used.

In particular, only identifiers (e.g. variable name) or properties typeofyou can use .
It can help you avoid the mistakes of writing code that you think is running, but that's not the case.

// @errors: 1005
declare const msgbox: () => boolean;
// type msgbox = any;
// ---cut---
// Meant to use = ReturnType<typeof msgbox>
let shouldContinue: typeof msgbox("Are you sure you want to continue?");

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[bumkeyy]

LGTM

[github-actions]

Merging because @bumkeyy is a code-owner of all the changes - thanks!