JSFiddle - React, Tailwind, and code Playground

by Desain Kode

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css">
<div id="content">Scroll &darr;</div>
<a href="#" id="back-to-top" title="Back to top"><i class='fa fa-chevron-up'></i></a>

CSS

#back-to-top {
  visibility: hidden;
  background-color: rgba(0, 0, 0, .7);
  color: #fff;
  width: 42px;
  height: 42px;
  text-align: center;
  line-height: 42px;
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 90;
  cursor: pointer;
  opacity: 0;
  border-radius: 3px;
  -webkit-transform: translateZ(0);
  transition: all .4s
}

#back-to-top .fa {
  font-size: 22px;
  vertical-align: middle
}

#back-to-top:hover {
  background-color: #46a3fa;
  color: #fff;
  opacity: 1;
}

#back-to-top.show {
  visibility: visible;
  opacity: 1;
}

#content {
  height: 2000px;
}

JavaScript

if ($('#back-to-top').length) {
  var scrollTrigger = 100, // px
    backToTop = function() {
      var scrollTop = $(window).scrollTop();
      if (scrollTop > scrollTrigger) {
        $('#back-to-top').addClass('show');
      } else {
        $('#back-to-top').removeClass('show');
      }
    };
  backToTop();
  $(window).on('scroll', function() {
    backToTop();
  });
  $('#back-to-top').on('click', function(e) {
    e.preventDefault();
    $('html,body').animate({
      scrollTop: 0
    }, 700);
  });
}