typescript-patterns

Const Types Pattern (REQUIRED)

// ✅ ALWAYS: Create const object first, then extract type
const STATUS = {
  ACTIVE: "active",
  INACTIVE: "inactive",
  PENDING: "pending",
} as const;

type Status = (typeof STATUS)[keyof typeof STATUS];

// ❌ NEVER: Direct union types
type Status = "active" | "inactive" | "pending";

Why? Single source of truth, runtime values, autocomplete, easier refactoring.

Flat Interfaces (REQUIRED)