TypeScript - Modules: import/export

ES Modules

// math.ts
export function add(a: number, b: number) { return a + b }
export default function sub(a: number, b: number) { return a - b }

// app.ts
import sub, { add } from './math.js';

Type-only imports

import type { User } from './types.js';

Re-exports

export { add } from './math.js';
export * from './more-math.js';

CommonJS interop

Use moduleResolution and esModuleInterop/allowSyntheticDefaultImports as needed; see Node Interop page.