JSFiddle - React, Tailwind, and code Playground

HTML

<div id="toTop" style="height:1000px;">
    I am gonna hide if you scoll up agaain!
</div>

JavaScript

var $toTop = $('#toTop');
$(window).scroll(function () {
    if ($(this).scrollTop() > 500) {
        $toTop.fadeIn();
    } else if ($toTop.is(':visible')) {
        $toTop.fadeOut();
    }
});