JSFiddle - React, Tailwind, and code Playground

HTML

<div id="a"> Outside Text
    <div id="b"> Inside Text</div>
</div>
<span id="result" style="color: blue;"></div>

JavaScript

var elements = document.getElementsByTagName('div');
function solution() {
    var text = '';
    var visited = [];
    for (var i = 0; i < elements.length; i++) {
      var found = false;
      for (var e = elements[i]; e != null; e = e.parentNode) {
        if (visited.indexOf(e) > -1) {
          found = true;
          break;
        }
      }
      if (!found) {
        text = text + ' ' + elements[i].innerText;
      	visited.push(elements[i]);
      }
    }
    document.getElementById('result').innerText = text;
}
function original() {
  var text = '';
  for (var i = 0; i < elements.length; i++) {
    text = text + ' ' + elements[i].innerText
  }
  document.getElementById('result').innerText = text;
}
// original();
solution();