Custom JS Keywords -> import

Hi again,

I’m looking for way how to use ‘external’ imports in custom JS library.
I’m trying to do something like this:

import { FileReader } from 'buffer';
async function fileReaderOwn(file_) {
  const reader = new FileReader()
  const x = reader.readAsDataURL(file_)
  return x

This is saved in module.js file, which I’m importing as JS library for Browser. Is there any way how to achieve usage of libraries?