Apa iku enums lan kapan sampeyan kudu nggunaake?

Question

Accepted Answer

An **enum** mendefinisikan satu set named constants. TypeScript duwe numeric lan string enums.

```ts
enum Direction { Up, Down, Left, Right } // numeric: Up=0, Down=1, ...
Direction.Up;        // 0
Direction[0];        // "Up" — numeric enums have a reverse mapping

enum Status {        // string enum — more readable values
  Active = "ACTIVE",
  Inactive = "INACTIVE",
}
Status.Active;       // "ACTIVE"
```

## A caveat: enums generate runtime code

Bedane paling TypeScript types (sing ilang ing compile time), regular `enum` ngirim JavaScript object menyang bundle mu. Mulane akeh tim milih **union of string literals** plus `as const`, sing murni type-level:

```ts
// often preferred — zero runtime cost, easy to read in logs
const Status = { Active: "ACTIVE", Inactive: "INACTIVE" } as const;
type Status = typeof Status[keyof typeof Status]; // "ACTIVE" | "INACTIVE"

// or simply:
type Direction = "up" | "down" | "left" | "right";
```

## const enum

```ts
const enum E { A, B } // inlined at compile time — no runtime object, but has tooling caveats
```

## Apa sing penting

Enums menehi jeneng sing meaningful kanggo fixed sets (states, roles, directions) lan nglompokke dheweke ana ing siji namespace.

Nanging amarga enums ngirim runtime code lan duwe quirks (numeric enums iku loosely checked), modern TypeScript asring milih **string-literal unions** kanggo simple cases — dheweke luwih ringan lan serialize secara natural.

Gunakake enums nalika sampeyan pengin namespacing utawa reverse mapping.