check-comments.js

(function showReaction(username, reaction){
  var elts = document.querySelectorAll('.js-details-container.outdated-diff-comment-container');
  var total = [];
  for (var i = elts.length - 1; i>=0; i--) {
    var elt = elts[i];
    var table = elt.querySelector('.js-inline-comments-container');
    if (!table || elt.classList.contains('open')) {
      continue;
    }
    var lastComment = table.children[table.children.length - 1];
    /* TODO: improve selection. This fails if several people reacted */
    var btns = lastComment.querySelectorAll('.reaction-summary-item[aria-label="'+ username +'"]');
    var flag = true;
    for (var j = btns.length - 1; j>=0; j--) {
      var labels = btns[j].value.split(' ');
      if (labels.indexOf(reaction) >= 0) {
        flag = false;
      }
    }
    if (!flag) {
      continue;
    }
    total.push(elt);
    var hdr = elt.querySelector('.discussion-item-header');
    var toggle = hdr.querySelector('.discussion-item-toggle-closed');

    hdr.style.backgroundColor = '#DD3535';
    toggle.click();
  }
  if (total.length) {
    alert(total.length+' comments were opened');
  } else {
    alert('nothing to open');
  }
})('elemeNtk0','tada'); /* your GitHub username && favorite reaction */