TypeScript fully supports ES6 module syntax for importing and exporting:

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

export function subtract(a: number, b: number): number {
  return a - b;
}

export default function multiply(a: number, b: number): number {
  return a * b;
}

export const PI = 3.14159;

// app.ts
import multiply, { add, subtract, PI } from './math';
import * as MathUtils from './math';

console.log(add(5, 3)); // 8
console.log(multiply(4, 2)); // 8
console.log(MathUtils.PI); // 3.14159