<div style="height: 200%;">
Đây là đầu trang
</div>
<div id="back-top">
<i class="fa fa-angle-up"></i>
</div>
#back-top {
width: 45px;
height: 45px;
line-height: 45px;
text-align: center;
position: fixed;
top:auto !important;
right: 20px;
bottom: 20px;
cursor: pointer;
margin: 0;
font-size: 30px;
background-color: #26C395;
color: #fff;
border-radius: 100%;
}
#back-top i{
display: block;
line-height: 41px;
}
jQuery(document).ready(function($){
$(window).scroll(function () {
if ($(window).scrollTop() != 0) {
$('#back-top').fadeIn();
} else {
$('#back-top').fadeOut();
}
});
$('#back-top').click(function () {
$('html, body').animate({ scrollTop: 0 }, 500);
});
});
<script src='//bizweb.dktcdn.net/100/005/795/themes/534730/assets/jquery-2.2.4.min.js?1495533194821' type='text/javascript'></script>
<script src="https://use.fontawesome.com/8cce71f27a.js"></script>
