How to define interoperable TypeScript modules (use Rollup.js to build cjs, mjs and umd modules)

module.ts

namespace MyName {

    export type MyType = string | number;

    export const myValue: MyType = createSampleValue();

    // internal
    function createSampleValue(): string {
      return "test";
    }

}

export = MyName;

tsconfig-partial.json

{
  "module": "commonjs",
  "moduleResolution": "node",
}

usage.js

// CommonJS

const MyName = require('my-module');

const x = MyName.myValue;

console.log(x);

usage.mjs

// ECMAScript Module (ESM)

import MyName from "my-module";

const x = MyName.myValue;

console.log(x);

usage.ts

// TypeScript

import MyName, { MyType } from "my-module";

const x: MyType = MyName.myValue;

console.log(x);