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faustienf/opaque.ts

Created March 22, 2022 13:07
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Opaque type in TypeScript
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opaque.ts
declare const opaque: unique symbol;
type Opaque<T, OpaqueType> = T & { readonly [opaque]: OpaqueType };
// examples
type Timestamp = Opaque<number, 'Timestamp'>;
const timestamp: Timestamp = Math.random() // Type 'number' is not assignable to type 'Timestamp'
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