Realizzare uno scrolltop con jQuery

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="demo-content">
	<nav>
		<h1>Page top</h1>
		<small>... scroll to bottom ...</small>
	</nav>
	<div class="container">
		<div class="clear">[Page content]</div>
	</div>
	<nav>
		<h1>Page bottom</h1>
		<small>... click button on right to return on top ...</small>
	</nav>
	<div id="go_top">
		<a href="#"><i class="fa fa-chevron-circle-up"></i></a>
	</div>
</div>

<!-- Credits -->
<div class="credits">
	<a class="btn-credits" href="https://code4life.it/guide/realizzare-uno-scrolltop-con-jquery/" target="_blank">Vedi articolo completo</a>
</div>

CSS

/*
 * TITLE:   Realizzare uno scrolltop con jQuery
 * AUTHOR:  Code4Life
 * WEBSITE: https://code4life.it/
 * ARTICLE: https://code4life.it/guide/realizzare-uno-scrolltop-con-jquery/
 */
 
/* Required snippet style */
#go_top {
	bottom: 110px;
	position: fixed;
	right: 10px;
	z-index: 99;
}

#go_top a {
	color: #33b5e5;
	font-size: 50px;
}

/* Demo style only */
.demo-content { margin-bottom: 70px; }

* {
	font-family: 'Roboto', sans-serif;
	margin: 0;
	padding: 0;
}

nav {
	background: #33b5e5;
	color: #fff;
	padding: .5rem 3rem;
}

.container {
	margin: auto;
	padding: 5rem 0;
	width: 80%;
}

.clear { line-height: 120vh; text-align: center; }

/* Credits */
@import url( 'https://fonts.googleapis.com/css?family=Roboto:300' );
.credits { background: #F3F5F6; border: solid 1px #CFD6D9; bottom: 40px; left: 0; padding: 10px; position: fixed; right: 0; text-align: center; z-index: 1000; }
.btn-credits { border: 2px solid #33b5e5; border-radius: 10em; color: #33b5e5 !important; display: inline-block; font-family: 'Roboto', sans-serif; font-size: .8rem; line-height: 1.25; padding: .85rem 2.13rem; text-decoration: none; text-transform: uppercase; transition: .2s ease-out; vertical-align: middle; }
.btn-credits:hover { background-color: #33b5e5; color: #fff !important; }

JavaScript

jQuery( function( $ ) {
	$( '#go_top a' ).on( 'click', function( e ) {
		e.preventDefault();
		$( 'html, body' ).stop().animate( {
			scrollTop: 50
		}, '500', 'swing' );
	} );
} );