Apa iku tipe-tipe kondisional lan tipe-tipe sing dipemetakan?

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Iki minangka alat **tipe-level programming** TypeScript — dheweke nglumpukake tipe-tipe anyar saka tipe-tipe sing wis ana. ## Tipe-tipe sing dipemetakan — ngowahi saben properti A mapped type iterates over the keys of a type and transforms each: ```ts type ReadonlyAll = { readonly [K in keyof T]: T[K] }; type Optional = { [K in keyof T]?: T[K] }; interface User { id: number; name: string; } type RO = ReadonlyAll; // { readonly id: number; readonly name: string } ``` `[K in keyof T]` loops over each key `K`; `T[K]` is that key's value type. Iki cara ngimplementasikake `Partial`, `Readonly`, lan `Required`. Sampeyan uga bisa ngremap kunci lan nambah modifiers (`-readonly`, `-?` removes them). ## Tipe-tipe kondisional — branching adhedhasar kondisi ```ts type IsString = T extends string ? "yes" : "no"; type A = IsString; // "yes" type B = IsString; // "no" ``` `T extends U ? X : Y` minangka if/else tingkat tipe. Kanthi `infer` sampeyan bisa *extract* tipe-tipe ing sajroning kondisi: ```ts type ElementOf = T extends (infer U)[] ? U : never; type E = ElementOf; // string ``` ## Nggabungake dheweke — conto nyata ```ts // Make only the function-valued properties optional type PartialMethods = { [K in keyof T]: T[K] extends Function ? T[K] | undefined : T[K]; }; ``` Mapped types uga **distribute** over unions in conditionals, enabling powerful transforms. ## Mengapa iku penting Mapped lan conditional types ngidini library-library ngenekake hubungan tipe sing presisi — dheweke ngimplementasikake utility types, power form/validation libraries, ORM query builders, lan API clients sing infer response shapes. Dheweke advanced, nanging ngerti dheweke nerangake *carane* TypeScript's type system bisa dadi ekspresif banget, lan ngidini sampeyan nggawe reusable type transforms tinimbang hand-writing variants.