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Improve first Example of "The satisfies Operator" in TS 4.9 r notes #3050

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Merged
Jake Bailey (jakebailey) merged 1 commit into from
Jun 5, 2024
Merged

Improve first Example of "The satisfies Operator" in TS 4.9 r notes #3050

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13 changes: 5 additions & 8 deletions packages/documentation/copy/en/release-notes/TypeScript 4.9.md
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Original file line number Diff line number Diff line change
Expand Up @@ -20,10 +20,7 @@ const palette = {
// ^^^^ sacrebleu - we've made a typo!
};

// We want to be able to use array methods on 'red'...
const redComponent = palette.red.at(0);

// or string methods on 'green'...
// We want to be able to use string methods on 'green'...
const greenNormalized = palette.green.toUpperCase();
```

Expand All @@ -42,8 +39,9 @@ const palette: Record<Colors, string | RGB> = {
// ~~~~ The typo is now correctly detected
};

// But we now have an undesirable error here - 'palette.red' "could" be a string.
const redComponent = palette.red.at(0);
// But we now have an undesirable error here - 'palette.green' "could" be of type RGB and
// property 'toUpperCase' does not exist on type 'string | RGB'.
const greenNormalized = palette.green.toUpperCase();
```

The new `satisfies` operator lets us validate that the type of an expression matches some type, without changing the resulting type of that expression.
Expand All @@ -61,8 +59,7 @@ const palette = {
// ~~~~ The typo is now caught!
} satisfies Record<Colors, string | RGB>;

// Both of these methods are still accessible!
const redComponent = palette.red.at(0);
// toUpperCase() methode is still accessible!
const greenNormalized = palette.green.toUpperCase();
```

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