我想制作类似于那些网站的效果,您可以向下滚动页面时会出现一些动画效果,如果向上滚动则会反转。我看到了一些库,例如这个,但我想知道是否有更简单的方法来实现这个效果?谢谢。
除此之外,我刚刚尝试了通过滚动更改关键帧的方法,使得在向下滚动时100%或动画结束时发生变化,在向上滚动时变为0%,但是它并没有起作用。
$(document).ready(function(){
var lastScrollTop = 0;
$(document).scroll(function(event){
var st = $(this).scrollTop();
if (st > lastScrollTop){
$('div').removeClass('scrollUp').addClass('scrollDown');
} else {
$('div').removeClass('scrollDown').addClass('scrollUp');
}
lastScrollTop = st;
});
});
body{
height: 150vh;
overflow-y: auto;
}
div {
width: 100px;
height: 100px;
position: fixed;
}
@keyframes myfirst {
0% {background: rgba(0,0,0,0); top: 0px;}
100% {background: rgba(0,0,0,1); top: 400px;}
}
.scrollDown{
animation-name: myfirst;
animation-duration: 5s;
animation-direction: alternate;
}
.scrollUp{
animation-name: myfirst;
animation-duration: 5s;
animation-direction: alternate-reverse;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>
$(document).ready(function(){
var lastScrollTop = 0;
$(document).scroll(function(event){
var st = $(this).scrollTop();
$('head>style').last().remove();
if (st > lastScrollTop){
$('head').append('<style>@keyframes myfirst{0%{background: rgba(0,0,0,0); top: 0px;}100%{background: rgba(0,0,0,1); top: '+st+'px;}}</style>');
$('div').removeClass('scrollUp').addClass('scrollDown');
} else {
$('head').append('<style>@keyframes myfirst{0%{background: rgba(0,0,0,0); top: '+st+'px;}100%{background: rgba(0,0,0,1); top: '+lastScrollTop+'px;}}</style>');
$('div').removeClass('scrollDown').addClass('scrollUp');
}
lastScrollTop = st;
});
});
body{
height: 150vh;
overflow-y: auto;
}
div {
width: 100px;
height: 100px;
position: fixed;
border: 1px solid black;
}
.scrollDown{
animation-name: myfirst;
animation-duration: 0s;
animation-direction: alternate;
}
.scrollUp{
animation-name: myfirst;
animation-duration: 0s;
animation-direction: alternate-reverse;
}
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
</head>
<div></div>
使用变换解决方案(无关键帧)
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>
<style>
body{
height: 150vh;
overflow-y: auto;
}
div {
width: 100px;
height: 100px;
position: fixed;
border: 1px solid black;
opacity: 0;
transition: opacity 0s ease;
background: rgb(0,0,0);
}
</style>
</head>
<body>
<div></div>
<script>
$(document).ready(function(){
var lastScrollTop = 0;
$(document).scroll(function(event){
var st = $(this).scrollTop();
$('head>style').last().remove();
if (st > lastScrollTop){
$('div').css({
opacity: function() {
var opacity = ((1 - (400 - st) / 400) * 0.8);
return opacity;
}, left: st
});
} else {
$('div').css({
opacity: function() {
var opacity = ((1 - (400 - st) / 400) * 0.8);
return opacity;
}, left: st
});
}
lastScrollTop = st;
});
});
</script>
</body>
</html>