What would be a way to implement star ratings?

[Secret-chest]

Here are my requirements:

• anyone can post comments, but only one comment may have a star rating (there is a bot to remove duplicate ratings somehow)
• the star rating is given in a format something like this:

  RATING: ⭐⭐⭐⭐
  rest of comment
  

• the average star rating should be possible to calculate using javascript