Modules, tsconfig & Declaration Files

TypeScript uses standard ES module syntax:

// money.ts export type Currency = "TZS" | "KES" | "USD"; export function format(amount: number, currency: Currency): string { … }

// app.ts import { format, type Currency } from "./money";

import type { X } (or the inline type modifier) imports only types — erased completely from the output, which avoids accidental runtime imports and helps bundlers.