JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    Original    
</div>

<p>
    ORIGINAL
    <span>Original blabla</span>
    <span>oRIGInal</span>
</p>

JavaScript

var elements = document.getElementsByTagName('*');

for (var i = 0; i < elements.length; i++) {
    console.log(elements[i]);
    var txt = elements[i].innerHTML.replace((new RegExp('(original)', 'gi')), "Alterada");
    elements[i].innerHTML = txt;
}