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Fix scoping of destructuring annotation note #2255

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Merged
merged 2 commits into from
Jul 24, 2023
Merged

Fix scoping of destructuring annotation note #2255

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8c96ccc
Fix scoping of destructuring annotation note
breyed Feb 6, 2022
755355a
Remove stray line
jakebailey Jul 24, 2023
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32 changes: 15 additions & 17 deletions packages/documentation/copy/en/handbook-v2/Object Types.md
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Expand Up @@ -157,23 +157,21 @@ Now `xPos` and `yPos` are both definitely present within the body of `paintShape

> Note that there is currently no way to place type annotations within destructuring patterns.
> This is because the following syntax already means something different in JavaScript.

```ts twoslash
// @noImplicitAny: false
// @errors: 2552 2304
interface Shape {}
declare function render(x: unknown);
// ---cut---
function draw({ shape: Shape, xPos: number = 100 /*...*/ }) {
render(shape);
render(xPos);
}
```

In an object destructuring pattern, `shape: Shape` means "grab the property `shape` and redefine it locally as a variable named `Shape`.
Likewise `xPos: number` creates a variable named `number` whose value is based on the parameter's `xPos`.

Using [mapping modifiers](/docs/handbook/2/mapped-types.html#mapping-modifiers), you can remove `optional` attributes.
>
> ```ts twoslash
> // @noImplicitAny: false
> // @errors: 2552 2304
> interface Shape {}
> declare function render(x: unknown);
> // ---cut---
> function draw({ shape: Shape, xPos: number = 100 /*...*/ }) {
> render(shape);
> render(xPos);
> }
> ```
>
> In an object destructuring pattern, `shape: Shape` means "grab the property `shape` and redefine it locally as a variable named `Shape`.
> Likewise `xPos: number` creates a variable named `number` whose value is based on the parameter's `xPos`.

### `readonly` Properties

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