// Can be used with https://github.com/xcv58/Custom-JavaScript-for-Websites-2
// This snippet is released under the terms of the CC0 license: https://creativecommons.org/publicdomain/zero/1.0/deed.en

const cache_key = 'hn_comments_views'
const cache = JSON.parse(localStorage.getItem(cache_key) || '{}')

document.querySelectorAll('.athing.comtr').forEach(comm => {
  if (!cache[comm.id]) {
    const span = document.createElement('span')
    span.innerHTML = '🔔' // :bell: emoji
    comm.querySelector('.comhead').append(span)
  }
  
  cache[comm.id] = true
})

localStorage.setItem(cache_key, JSON.stringify(cache))