css 来自http://www.paulund.co.uk/how-to-create-an-animated-scroll-to-top-with-jquery

Posted 2021-05-13

$(document).ready(function(){
	
	//Check to see if the window is top if not then display button
	$(window).scroll(function(){
		if ($(this).scrollTop() > 100) {
			$('.scrollToTop').fadeIn();
		} else {
			$('.scrollToTop').fadeOut();
		}
	});
	
	//Click event to scroll to top
	$('.scrollToTop').click(function(){
		$('html, body').animate({scrollTop : 0},800);
		return false;
	});
	
});

<a href="#" class="scrollToTop">Scroll To Top</a>

.scrollToTop{
	width:100px; 
	height:130px;
	padding:10px; 
	text-align:center; 
	background: whiteSmoke;
	font-weight: bold;
	color: #444;
	text-decoration: none;
	position:fixed;
	top:75px;
	right:40px;
	display:none;
	background: url('arrow_up.png') no-repeat 0px 20px;
}
.scrollToTop:hover{
	text-decoration:none;
}