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And types

@RiccardoOdone•Suggest a tip•

Dry up code by extracting the common type.

type Alpha = { a: string, b: number, c: boolean, d: Date, w: W }
type Beta = { a: string, b: number, c: boolean, d: Date, z: Z }

const extractAFromAlpha = (alpha: Alpha): string => alpha.a
const extractAFromBeta = (beta: Beta): string => beta.a
// ⛔️ Looks suspiciously repeated

type Base = { a: string, b: number, c: boolean, d: Date }
type Alpha = Base & { w: W }
type Beta = Base & { z: Z }

const extractAFromBase =
  (base: Base): string => base.a // ✅ One function
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