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?

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

Shrike · Accepted Answer · 2018-04-06 11:10:47Z

1

Library

tsconfig.json:

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "noEmitHelpers": true
  },
}

module.ts:

export class MyClass {
  static Version: string = "1.0";
}

When we compile this module we'll get:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var MyClass = /** @class */ (function () {
    function MyClass() {
    }
    MyClass.Version = "1.0";
    return MyClass;
}());
exports.MyClass = MyClass;

TS Client

client.ts:

import {MyClass} from "./../src/module";

console.log(MyClass.Version);

compile and run node client.js - see "1.0"

JS Client

Just grad the same code from compiled ts client :

var module_1 = require("./../src/module");
console.log(module_1.MyClass.Version);

same output obviously

answered Apr 6, 2018 at 11:10

Shrike

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Comments

Shadab Faiz · Accepted Answer · 2018-04-06 11:15:46Z

0

Using a typescript file in typescript.

Assuming B.ts is the typescript file that you want to use in A.ts, then:

    import { B's module that are exported } from 'path/to/B';  // notice there is no extension mentioned here.

Also B must have a export module in it.

Using a ts file in a js file.

B.ts = file which you want to use in your main file.
A.js = your main file.
In your A.js:

    var external = require('path/to/B'); // notice there is no extension mentioned here.

answered Apr 6, 2018 at 11:15

Shadab Faiz

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Jimmy Breck-McKye · Accepted Answer · 2018-04-06 13:11:09Z

0

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');

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

answered Apr 6, 2018 at 13:11

Jimmy Breck-McKye

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