JSFiddle - React, Tailwind, and code Playground

HTML

<div id="up">UPPPP</div>

CSS

body, html{
    position: relative;
    height: 1000px;
}

div#up{
    position: absolute;
    padding: 50px;
    background-color: blue;
}

JavaScript

$('#up').click(function() {
    $('html,body').animate({
        scrollTop: 0
    }, 'slow');
});
$(window).scroll(function() {
    if ($(window).scrollTop() > 50) {
        $('#up').fadeOut();
    } else {
        $('#up').fadeIn();
    }
});