Writing a Node module in TypeScript for consumption by both TS and JS projects

Question

I have an Express middleware project written in TypeScript. I'd like to consume it in both JS & TS based Node projects.

I'm having trouble configuring my projects to ensure that

• the upstream project is outputting modules that can be consumed by Node
• my module can be consumed in JS projects in the format myGreatFunction = require('myGreatFunction') // typeof = function
• my module can be consumed in the format import myGreatFunction from 'myGreatFunction' // typeof = function
• my module is not being either output as an object with a .default when that is not expected, or, vice-versa, not being done so when that is indeed expected.

It feels as though I can only achieve some of these aims but not others.

What is the correct incantation of TSConfig properties (upstream & downstream) to ensure this is so?

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In the end I settled on a compromise - see below.

Answer 1

In the end I settled on a compromise:

Library TSConfig:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "declaration": true
  }
}

Library:

export = function myGroovyFunction() {...}

Downstream project, TypeScript

import * as myGroovyFunction from 'mygroovyfunction';

Downstream project, JavaScript

const myGroovyFunction = require('mygroovyfunction');

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The TypeScript import isn't quite as concise as I'd like, but I can deal.