Apa iku template literal types?

Question

Accepted Answer

**Template literal types** ngandakake kowe bumuo tipe string literal anyar kanthi interpolasi tipe-tipe liyane menyang template — manipulasi string ing tingkat *type*. ```ts type Greeting = `Hello, ${string}`; const a: Greeting = "Hello, world"; // ✅ const b: Greeting = "Hi there"; // ❌ doesn't match the pattern ``` ## Nggabung karo unions — kabur distribute ```ts type Color = "red" | "blue"; type Shade = "light" | "dark"; type Variant = `${Shade}-${Color}`; // "light-red" | "light-blue" | "dark-red" | "dark-blue" — all combinations ``` Kompiler nggembangake saben kombinasi saka unions — migunani kanggo ngasilake valid string keys (CSS classes, event names, route patterns) kanthi otomatis. ## Pola real-world: typed event names ```ts type Entity = "user" | "post"; type Event = `${Entity}:${"created" | "deleted"}`; // "user:created" | "user:deleted" | "post:created" | "post:deleted" function on(event: Event, cb: () => void) {} on("user:created", () => {}); // ✅ on("user:updated", () => {}); // ❌ not a valid event ``` ## Karo key remapping lan intrinsic helpers ```ts type Getters = { [K in keyof T & string as `get${Capitalize}`]: () => T[K]; }; // { name: string } → { getName: () => string } ``` `Uppercase`, `Lowercase`, `Capitalize`, `Uncapitalize` minangka intrinsic helpers sing built-in. ## Ngapa iku penting Template literal types ngasilake string-based APIs sing type-safe: route params, event systems, CSS-in-JS, ORM column names. Simbah saka nampa `string` apa wae, kowe bisa mbatasi menyang set string sing valid lan presisi, generated — nangkep typos ing compile time ing papan sing biasane stringly-typed.