JSFiddle - React, Tailwind, and code Playground

HTML

<div class="idea__comment"  data-commentid="%id%">
  <div class="comment__user">
    <div class="comment__username" data-userid="%user_id%">
      <a href="/user/%user_id%">%firstname% %lastname%</a>
    </div>
    <div class="comment__date">Добавлено: <!-- DATE --></div>
    <div class="clear"></div>
  </div>
  <figure class="comment__avatar">
    <img src="/i/noimage.jpg" class="img-responsive">
  </figure>
  <div class="comment__content">
    <!-- COMMENT TEXT -->
  </div>
  <div class="clear"></div>
  <div class="comment__panel">
    <button class="comment__btn comment__btn-cite">Цитировать</button>
  </div>
  <div class="clear"></div>
</div>

JavaScript

window.onload = function ()
    {
            let citeBtn = document.querySelectorAll('.idea__comment');

            for (let i = 0; i < citeBtn.length; i++) {
                citeBtn[i].onclick = citeComment;
            }
    };

function citeComment()
    {

        let cite = this.parentElement;
        let data = {
            userId: cite.dataset.userid,
            commentId: cite.dataset.commentid,
        };

        let i = 0;

        while (i < 5)
        {
          cite = cite.previousElementSibling;

          if (cite.classList.contains('comment__content'))
          {
              data['text'] = cite.innerText;
          }
          else if (cite.classList.contains('comment__user'))
          {
              data['date'] = cite.children[1].innerText;
          }

          i++;
        }

        console.log(data);
    }