JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<div style="height: 2000px">Scroll down!</div>

JavaScript

var alerted = false;
$(window).scroll(function () {
    if ($(window).scrollTop() + $(window).height() > $(document).height() - 100) {
        if (!alerted) {
            alert("bottom!");
            alerted = true;
        }
    }
    else alerted = false;
});