Typed totals by status in TypeScript
TypeScript interview exercise on TypeScript, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
Declare type Status = "paid" | "pending" | "refunded" and interface Order { id: number; total: number; status: Status }. Then write totalsByStatus(orders: Order[]): Record<Status, number> returning summed totals with all three keys present.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.