JSFiddle - React, Tailwind, and code Playground

HTML

<div class="content" style="display: none";>a</div>
<div class="content" style="display: block;">b</div>
<div class="content" style="display: none";>c</div>
<div class="content" style="display: none";>d</div>
<div class="content" style="display: none";>e</div>

JavaScript

var elements = document.getElementsByClassName("content");

for(i = 0; i < elements.length; i++) 
{
     if (elements[i].style.display == 'block')
     {
          // This is the visable div   
         alert('This elements[i] has a display of block: ' + elements[i].style.display);
     }
}