css 回到顶部按钮

Posted 2021-05-13

jQuery(document).ready(function($){
	// browser window scroll (in pixels) after which the "back to top" link is shown
	var offset = 300,
		//browser window scroll (in pixels) after which the "back to top" link opacity is reduced
		offset_opacity = 1200,
		//duration of the top scrolling animation (in ms)
		scroll_top_duration = 800,
		//grab the "back to top" link
		$back_to_top = $('.cd-top');

	//hide or show the "back to top" link
	$(window).scroll(function(){
		( $(this).scrollTop() > offset ) ? $back_to_top.addClass('cd-is-visible') : $back_to_top.removeClass('cd-is-visible cd-fade-out');
		if( $(this).scrollTop() > offset_opacity ) { 
			$back_to_top.addClass('cd-fade-out');
		}
	});

	//smooth scroll to top
	$back_to_top.on('click', function(event){
		event.preventDefault();
		$('body,html').animate({
			scrollTop: 0 ,
		 	}, scroll_top_duration
		);
	});

});

.cd-top {
	display: inline-block;
	height: 40px;
	width: 40px;
	position: fixed;
	bottom: 20px;
	right: 20px;
	box-shadow: 0 0 10px rgba(0, 0, 0, 0.05);
	overflow: hidden;
	text-indent: 100%;
	white-space: nowrap;
	background: rgba(3, 165, 225, 0.8) url(images/cd-top-arrow.svg) no-repeat center 50%;
	visibility: hidden;
	opacity: 0;
	-webkit-transition: opacity .3s 0s, visibility 0s .3s;
	-moz-transition: opacity .3s 0s, visibility 0s .3s;
	transition: opacity .3s 0s, visibility 0s .3s;
	z-index: 1;
}
.cd-top.cd-is-visible, .cd-top.cd-fade-out, .no-touch .cd-top:hover {
	-webkit-transition: opacity .3s 0s, visibility 0s 0s;
	-moz-transition: opacity .3s 0s, visibility 0s 0s;
	transition: opacity .3s 0s, visibility 0s 0s;
}
.cd-top.cd-is-visible {
	visibility: visible;
	opacity: 1;
}
.cd-top.cd-fade-out {
}
.cd-top:hover {
	opacity: 0.5;
}
.no-touch .cd-top:hover {
	background-color: #e86256;
	opacity: 1;
}

/* Device specific conditional statements */

@media only screen and (min-width:768px) {
.cd-top {
	right: 20px;
	bottom: 20px;
}
}

@media only screen and (min-width:1024px) {
.cd-top {
	height: 60px;
	width: 60px;
	right: 30px;
	bottom: 30px;
}
}