How to export Javascript class which can be shared by NodeJS and ES6?

I have an Electron app integrated with Flask server. The app has both HTML loaded by Flask server (flask-page.html ES6) and Electron renderer (render-page.html NodeJS).

I want to share a class defined in a file for Flask and Renderer to avoid duplicated code, as class is exactly the same, but with different export/import.

Now, it's defined in 2 files as followings:

sharedclass-nodejs.js

    class sharedClass {
      sameMethod() {

      }
    }

    module.exports = {sharedClass}

sharedclass-es6.js

    export class sharedClass {
      sameMethod() {

      }
    }

load-flask.js

    import {sharedClass} from "sharedclass-es6.js"

flask-page.html (Flask server)

    <script type="module" src="sharedclass-es6.js"></script>
    <script type="module" src="load-flask.js"></script>

load-render.js

    const {sharedClass} = require("sharedclass-nodejs.js")

render-page.html (Electron render UI)

    <script src="sharedclass-nodejs.js"></script>

Is it possible to define 1 copy of "class sharedClass" in 1 file, such as NodeJS style export, and use it in ES6?