hbroer / import-test

Minimal setup of a project failed building with two levels of dependencies

Webpack/TS Resolve Problem

Package toplevel requires secondlevel Package secondlevel requires firstlevel

Build of package toplevel fails with:

ERROR in ./node_modules/secondlevel/dist/index.mjs 1:73-74
Can't import the named export 'FirstLevel' from non EcmaScript module (only default export is available)
 @ ./src/index.ts

When it fails?

When ever the extension of the module is mjs, like index.mjs or index.module.mjs it fails:

{
  "main": "dist/index.js",
  "module": "dist/index.mjs"
}

and also

{
  "main": "dist/index.js",
  "module": "dist/index.module.mjs"
}

When does it work?

When the extension of the module is set to js.

{
  "main": "dist/index.js",
  "module": "dist/index.module.js"
}

OR when building with Webpack 5 Beta then it also works with .mjs extensions.

Steps to reproduce:

cd firstlevel
rm -rf node_modules package-lock.json
npm install
npm pack
cd ../secondlevel
rm -rf node_modules package-lock.json
npm install
npm pack
cd ../toplevel
rm -rf node_modules package-lock.json
npm install
npm run build