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Module

x/tsafe/id.ts

🔩 The missing TypeScript utils
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/** https://docs.tsafe.dev/id */export const id = <T>(x: T) => x;
/** * Ensure that a that a specific type that we are declaring extends a more generic type * * Use case example 1: * * type MyObject = { * p1: string; * p2: string; * a: string; * b: string; * }; * * We want to define a type that consist in an union of * all the property name that are letters: * * type AlphabeticalKeys = Id<keyof MyObject, "a" | "b">; * * Here AlphabeticalKeys is "a" | "b" but it's better than * simply writing it explicitly as we get autocompletion * and we can't include a property name that does not exist on MyObject. * * Use case example 2: * * We want to declare object type that only take string or number * as key value: * * export type MyObject = Id<Record<string, string | number>, { * p1: string; * p2: number; * }>; * * If later on someone adds "p3": string[] he will get a type error. * */export type Id<Generic, Specific extends Generic> = Specific;