JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <span>This</span>
  <span>Example</span>.

  <div> Here is my example text. I will be looking to highlight the word <span class="blue-underline">example.</span> </div>
</body>

CSS

.highlight {
  background-color: yellow;
}

.blue-underline{
  border-bottom: 1px solid blue;
}

JavaScript

let target = 'example';
var text = document.querySelector('body').textContent;

var regex = new RegExp('(' + target + ')', 'ig');
const newtext = text.replace(regex, '<a href="#" class="highlight">$1</a>');

text.innerHTML = newtext;