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Extract<Type, Union> #9

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nmsn opened this issue Dec 6, 2022 · 1 comment

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nmsn commented Dec 6, 2022 •

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Constructs a type by extracting from Type all union members that are assignable to Union.

type T0 = Extract<"a" | "b" | "c", "a" | "f">;
// type T0 = "a"

type T1 = Extract<string | number | (() => void), Function>;
// type T1 = () => void

Contributor Author

nmsn commented Dec 6, 2022

/**
 * Extract from T those types that are assignable to U
 */
type Extract<T, U> = T extends U ? T : never;

nmsn added the TypeScript label

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