"Must use import to load ES Module" problem

[karianpour]

With node 12 , when I tries the sample I got the following error.
It looks like it cannot import the module.
Does it support node 12?

$> node -r esm
Welcome to Node.js v12.16.1.
> import LatLon from 'geodesy/latlon-spherical.js';
.../node_modules/geodesy/latlon-spherical.js:1
Uncaught:
Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: .../node_modules/geodesy/latlon-spherical.js
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1174:13) {
  code: 'ERR_REQUIRE_ESM'
}

[long1eu]

Similar issue here.

[chrisveness]

Some very strange behaviour going on here.

I can replicate this issue on a fresh npm install using e.g. Node.js v12.16.1 – but if I switch to an earlier version (v12.15.0 or earlier), then switch back to v12.16.1, it works correctly.

$ npm install geodesy esm

Using 12.16.1 fails:

$ nvm use 12.16.1
$ node -r esm
> import LatLon from 'geodesy/latlon-spherical.js';
/tmp/node_modules/geodesy/latlon-spherical.js:1
Uncaught:
Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /tmp/node_modules/geodesy/latlon-spherical.js
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1174:13) {
  code: 'ERR_REQUIRE_ESM'
}
>

Switching to an earlier version works:

$ nvm use 12.15.0
$ node -r esm
> import LatLon from 'geodesy/latlon-spherical.js';
> new LatLon(51, 1)
LatLonSpherical { _lat: 51, _lon: 1 }
> 

Switching back to 12.16.1 then works:

$ nvm use 12.16.1
$ node -r esm
> import LatLon from 'geodesy/latlon-spherical.js';
> new LatLon(51, 1)
LatLonSpherical { _lat: 51, _lon: 1 }
> 

I have already logged an issue on the esm repository relating to this.

Versions prior to 12.16.0 appear to work ok (though 12.14.0 & 12.15.0 thow out an error message).

If you are able to upgrade to Node.js v13.2.0+, esm is no longer required (though import is not available in the REPL).

$ nvm use 13.2.0
$ cat test.js
import LatLon from 'geodesy/latlon-spherical.js';
console.log(new LatLon(51, 1));
$ node test.js
(node:26167) ExperimentalWarning: The ESM module loader is experimental.
LatLonSpherical { _lat: 51, _lon: 1 }
$ 

[chrisveness]

It appears that ES modules can be loaded using the esm package in Node.js v8.0.0–v12.15.0, and natively in Node.js v13.2.0+. I'm not sure if the gap between those two options will ever get fixed.

[montumodi]

@chrisveness Is there a workaround for this issue? We are currently using it in lambda function and it is breaking with the same error? We are using node version 12.x in lambda function

[jomel]

@montumodi
Use v1 branch. ;) It's ES5.

[montumodi]

Thanks @jomel. We downgraded it to v1 for this but was wondering if there is any other fix or workaround available.

[chrisveness]

Node.js is having a slightly difficult time in migrating from CJS to ESM, I think.

This library was originally ES5 for browser only. At some point I added module.export statements for it to work with Node.js. Version 2 was a major enhancement, which was only possible with ES modules (I didn't want to get involved with Babel build steps).

In Node.js, CJS & ESM have fundamental differences, which the node team are slowly reconciling.

As far as I am aware, current options for using the geodesy library are:

• modern browsers (except Opera mini/mobile): geodesy@2
• Node.js v13.2.0+: geodesy@2 with native module loader
• Node.js v8.0.0–v12.15.0: geodesy@2 with the esm package
• older browsers: geodesy@1
• other versions of Node.js: geodesy@1

[strarsis]

I get the same error with node v15.3.0 and with the recommended flags enabled.

node --experimental-modules -r esm test.js

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: [...]/node_modules/geodesy/latlon-ellipsoidal-vincenty.js
    at new NodeError (node:internal/errors:278:15)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1119:13) {
  code: 'ERR_REQUIRE_ESM'
}

[mickeyjohn]

Hi,

I got the same error message when trying to use V2 on CommonJs modules. Thus, I migrated to using v2 with some code changes as examples below. Basically, in recent Node versions > v12.x, you can use dynamic module loading directly. Note that dynamic ES modules loading works asynchronously.

async function Func() {
  // Dynamically load ES geodesy v2 modules.
  const llsMod = await import('geodesy2/latlon-spherical.js');
  LatLonSP = llsMod.default;
  const utmMod = await import('geodesy2/utm.js');
  Utm = utmMod.default;
  LatLon = utmMod.LatLon;

 // Then use as:
  const utm1 = new Utm(..);
  const latlng = new LatLon();
  ... 
}