JSFiddle - React, Tailwind, and code Playground

HTML

<br>
<br><br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>

JavaScript

window.onscroll = function(ev) {
    if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight) {
        alert("you're at the bottom of the page");
    }
};