JSFiddle - React, Tailwind, and code Playground

HTML

<body class="example">

  <div class="img-container">
    <img src="https://dummyimage.com/320x120/000/fff" alt="dummy image">
    <div class="img-infobox">
      <p>This is a dummy image from https://dummyimage.com/</p>
    </div>
  </div>

</body>

JavaScript

var imgContainer = document.querySelector('.img-container');

var bodyTag = document.getElementsByTagName('body');

var bodyClassName = bodyTag.classname;

  if (bodyTag.classList.contains("example")) {
  
    imgContainer.onclick = infoBox;

    function infoBox(event) {
  
      alert('img-container has been clicked and body has class "example"');    
    }
  }