Correct way to setup worker from 2.6.x to 4.8.x

[afacchini]

I'm currently having issues with pdfjs-dist latest version (4.8.69). In our webapp (react-ts-webpack) we already have an old version of the lib (2.6.347).

As we compile ES5 code for legacy requirements, I needed to first parse the files with babel, to be able to import them.

Now my main issue is about the worker setup. I tried different approaches:

Import webpack.mjs from the build/ folder as stated in the WIKI.
Build correctly, error in the console import.meta.url can't be used outside module

2. Use our current implementation:

import * as pdfjs from 'pdfjs-dist';
import PdfjsWorker = require('worker-loader!pdfjs-dist/build/pdf.worker.js');

if (typeof window !== 'undefined' && 'Worker' in window) {
    pdfjs.GlobalWorkerOptions.workerPort = new PdfjsWorker();
}

But with the new files:

import * as pdfjs from 'pdfjs-dist/build/pdf.mjs';
import PDFWorker = require('worker-loader!pdfjs-dist/build/pdf.worker.mjs');

Build correctly too, but in the console it throws an error about importing an ESM module in a .cjs file

3. Same as above, but import the worker from the legacy folder:

import * as pdfjs from 'pdfjs-dist/legacy/pdf.mjs';
import PDFWorker = require('worker-loader!pdfjs-dist/legacy/pdf.worker.mjs');

Error in the console about __webpack_require__ being an empty object (error is: could not call property .d of undefined, reading __webpack_require__.d())

Does someone had similar issues? Thanks in advance