Nest.js: Unable to import

[theheckwr]

Problem

Compilation fails when using tle.js with nest.js:

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: <redacted>/node_modules/tle.js/dist/tlejs.umd.js
require() of ES modules is not supported.
require() of <redacted>/node_modules/tle.js/dist/tlejs.umd.js from <redacted>/dist/services/spacecraft-data.service.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
Instead rename tlejs.umd.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from <redacted>/node_modules/tle.js/package.json.

    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1089:13)
    at Module.load (internal/modules/cjs/loader.js:937:32)
    at Function.Module._load (internal/modules/cjs/loader.js:778:12)
    at Module.require (internal/modules/cjs/loader.js:961:19)
    at require (internal/modules/cjs/helpers.js:92:18)
    at Object.<anonymous> (<redacted>/src/services/spacecraft-data.service.ts:5:1)
    at Module._compile (internal/modules/cjs/loader.js:1072:14)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1101:10)
    at Module.load (internal/modules/cjs/loader.js:937:32)
    at Function.Module._load (internal/modules/cjs/loader.js:778:12)

Workaround

Remove the "type": "module", line from the package.json

Solution

I don't know (yet). Maybe remove the line and everything would be fine? Or does that cause other problems?

[davidcalhoun]

Thanks for the heads up, it looks like Nest.js doesn't yet support ES Modules: nestjs/nest#8736 (also see nestjs/nest#7021)

The good news is that it's a quick fix for you - you can tell it to explicitly use the CommonJS dist instead:

const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

I verified this works by running their TypeScript starter project and outputting some test code in their app.service.ts Hello World (note that I'm using Node 16.13.1):

import { Injectable } from '@nestjs/common';
const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

@Injectable()
export class AppService {
  getHello(): string {
    return `Hello World! ${JSON.stringify(getLatLngObj(tle))}`;
  }
}

[theheckwr]

Okay, thanks for the info and the "temporary" solution.
That's way better than my workaround. I've implemented it and it works so far.
Let's hope they'll implement it soon.

[davidcalhoun]

Great, glad that works! I am seeing a similar error with a simple Node project so I think I may be packaging it a bit wrong as well, looking into this!

[davidcalhoun]

In tle.js 4.5.0 I've added Node.js conditional exports support which seems to resolve the issue!

[theheckwr]

Unfortunately when I try to import this version with TypeScript into my Nest.js project, that fails with a "Can't find module declaration or corresponding type declaration" (Even my IDE (vs-code) shows this...).
Maybe this is a problem again with Nest.js but it looks like a TypeScript thing to me. Maybe something with my TypeScript config?

Additionally the other way you described before now gives an error:

Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './dist/tlejs.cjs' is not defined by "exports" in <redacted>/node_modules/tle.js/package.json
    at throwExportsNotFound (internal/modules/esm/resolve.js:299:9)
    at packageExportsResolve (internal/modules/esm/resolve.js:522:3)
    at resolveExports (internal/modules/cjs/loader.js:449:36)
    at Function.Module._findPath (internal/modules/cjs/loader.js:489:31)
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:875:27)
    at Function.Module._load (internal/modules/cjs/loader.js:745:27)
    at Module.require (internal/modules/cjs/loader.js:961:19)
    at require (internal/modules/cjs/helpers.js:92:18)
    at Object.<anonymous> (<redacted>/src/services/spacecraft-data.service.ts:5:84)
    at Module._compile (internal/modules/cjs/loader.js:1072:14)

[davidcalhoun]

Oof, thanks for the heads up, I'm not sure what's going on there. As a workaround you'll have to lock it down to the prior version for now (npm i tle.js@4.4.0). Sorry for the hassle!

[theheckwr]

Yes, that's what I did already.
But thanks anyways for the help so far.

[davidcalhoun]

When you have a chance, please try again with 4.5.3, I believe I finally tracked down the issue! Thanks again.

[theheckwr]

Okay, I tested it.
It works so far. No errors and the functions I'm using are executing normally, as far as I see. Even with Nest.js.
Thanks very much!

[davidcalhoun]

Woo! Good stuff, thanks for your patience!

[thkruz]

@davidcalhoun can you close this?

[davidcalhoun]

Sounds good, closing this out!