The article mentions Python, Requests and BeautifulSoup.

Here's a short example that scrapes HN Favorites. [0]

  #!/usr/bin/env python3
  
  import requests
  from bs4 import BeautifulSoup
  
  username = input('username: ')
  
  # session uses connection pooling, often resulting in faster execution.
  session = requests.Session()
  
  base = 'https://news.ycombinator.com/'
  path = f'favorites?id={username}'
  while path:
      r = session.get(base + path)
      s = BeautifulSoup(r.text, 'html.parser')
      for a in s.select('a.storylink'):
          print(a.text, a['href'])
      more = s.select_one('a.morelink')
      path = more['href'] if more else None

[0] Python: https://github.com/gabrielsroka/gabrielsroka.github.io/blob/...

[1] JavaScript, runs in browser with a UI: https://github.com/gabrielsroka/gabrielsroka.github.io/blob/...

Use this an example, but for real stuff prefer using the official API https://github.com/HackerNews/API