need help converting this python script to javascript

check_remote_or_local.py

import pathlib
import requests
import sys


def main():
    source = 'https://s4.anilist.co/file/anilistcdn/media/anime/banner/109287-Du3UxrOnIS4w.jpg'
    fallback_source = 'D:/test.png'

    try:
        # check if the given source is a url and image can be pulled from url, but don't actually download the file
        requests.get(source)
    except requests.exceptions.RequestException:
        # if nothing can't be pulled from the given url, check if the given source is a local file path
        if not (pathlib.Path(source).exists and pathlib.Path(source).is_file()):
            # if nothing can't be find locally, use a fallback source, which is a local file that must present
            source = fallback_source
            
            # if fallback source can't be find, print out an html <img> element with empty source
            if not (pathlib.Path(source).exists and pathlib.Path(source).is_file()):
                sys.exit(f'<img src="" alt="alternate">')

    sys.exit(f'<img src="{source}" alt="alternate">')


if __name__ == '__main__':
    main()

converted using an online converter but I don't think this is correct...

import * as pathlib from 'pathlib';
import * as requests from 'requests';
import * as sys from 'sys';

function main() {
  var fallback_source, source;
  source = "https://s4.anilist.co/file/anilistcdn/media/anime/banner/109287-Du3UxrOnIS4w.jpg";
  fallback_source = "D:/test.png";

  try {
    requests.get(source);
  } catch (e) {
    if (e instanceof requests.exceptions.RequestException) {
      if (!(new pathlib.Path(source).exists && new pathlib.Path(source).is_file())) {
        source = fallback_source;

        if (!(new pathlib.Path(source).exists && new pathlib.Path(source).is_file())) {
          sys.exit(`<img src="" alt="alternate">`);
        }
      }
    } else {
      throw e;
    }
  }

  sys.exit(`<img src="${source}" alt="alternate">`);
}

if (__name__ === "__main__") {
  main();
}