JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent first">
  <ul class="parent2">
    <li class="parent3">
      <button class="target">Купить</button>
    </li>
  </ul>
</div>
<div class="parent second">
  <ul class="parent2">
    <li class="parent3">
      <button class="target">Купить</button>
    </li>
  </ul>
</div>
<div class="parent third">
  <ul class="parent2">
    <li class="parent3">
      <button class="target">Купить</button>
    </li>
  </ul>
</div>

CSS

.parent {padding:0 8px;border:1px solid red;margin:8px 0;}
.parent2 {padding:8px;border:1px solid green;list-style:none;}
.parent3 {padding:8px;border:1px solid blue;}
.target {color:red;}

JavaScript

var parents = document.querySelectorAll('.parent');
for (var i = 0, parent; parent = parents[i]; i++)
    parent.onclick = function(e) {
              if (e.target.className == 'target')                              alert(this.className);
           };