JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test"><h1>Some Stuff</h1></div>
<div class="woot woory what">ok what now?</div>
<div id="ok">findme i bet you cant!</div>

JavaScript

var word = "findme",
    queue = [document.body],
    curr
;
while (curr = queue.pop()) {
    if (!curr.textContent.match(word)) continue;
    for (var i = 0; i < curr.childNodes.length; ++i) {
        switch (curr.childNodes[i].nodeType) {
            case Node.TEXT_NODE :
                if (curr.childNodes[i].textContent.match(word)) {
                    alert("Found!");
                }
                break;
            case Node.ELEMENT_NODE :
                queue.push(curr.childNodes[i]);
                break;
        }
    }
}