JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <a href="#" id="backtotop">Top</a>
</div>

CSS

#wrapper {height:2000px; background:#ccc; position:relative;}
#backtotop{ position: absolute; top:800px; left:0; display:none }

JavaScript

$(window).scroll(function() {
    if($(this).scrollTop() > 200) {
        $('#backtotop').fadeIn();
    } else {
        $('#backtotop').fadeOut();
    }
});



$('#backtotop').bind('click', function(e) {
    e.preventDefault();
    $('body,html').animate({scrollTop:0},800);
});