正文

JS——scroll动画

IP云
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08/30
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固定导航栏

1、计算导航栏到顶部的距离值

2、当scrollTop值大于这个距离值就添加定位，当小于距离值后解除定位

注意事项：当导航栏添加定位之后，导航栏就脱离了文档流，也就是不占位了，下面的盒子就会顶上来，所以要给下面盒子添加padding-top值

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
} body {
height: 5000px;
} .box1 {
height: 40px;
background-color: pink;
overflow: hidden;
} .box2 {
height: 50px;
background-color: yellow;
font: 500 20px/50px "simsun";
text-align: center;
} .box3 {
width: 820px;
height: 512px;
margin: 10px auto;
} .fixed {
position: fixed;
width: 100%;
top: 0;
left: 0;
}
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2">导航栏</div>
<div class="box3">
<img src="data:images/nba.jpg">
</div>
<script>
var banner = document.getElementsByTagName("div")[0];
var nav = document.getElementsByTagName("div")[1];
var lastDiv = document.getElementsByTagName("div")[2];
window.onscroll = function () {
if (scroll().top >= banner.offsetHeight) {
nav.className = "box2 fixed";
lastDiv.style.paddingTop = nav.offsetHeight + "px";
} else {
nav.className = "box2";
lastDiv.style.paddingTop = "0px";
}
} function scroll() {
return {
"top": window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop,
"left": window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft
};
}
</script>
</body>
</html>

两侧跟随广告

1、之前都是offsetLeft计算x轴上的移动，现在是计算y轴方向的移动

2、鼠标滚动之后，遮盖的距离scrollTop值，需要和广告之前的定位Top值进行相加才是滚动的真正目标值

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
} body {
height: 5000px;
} .box1 {
width: 800px;
margin: 50px auto;
font: 500 25px/45px "simsun";
color: red;
text-align: center;
} span {
position: absolute;
top: 300px;
width: 40px;
height: 120px;
background: rgba(255, 142, 142, 0.3);
font: 600 30px/60px "simsun";
color: red;
text-align: center;
} .ad-left {
left: 400px;
} .ad-right {
right: 400px;
}
</style>
</head>
<body>
<span class="ad-left">广<br>告</span>
<span class="ad-right">广<br>告</span>
<div class="box1">
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
</div>
<script>
var sp1 = document.getElementsByTagName("span")[0];
var sp2 = document.getElementsByTagName("span")[1]; window.onscroll = function () {
animate(sp1, scroll().top + 300);
animate(sp2, scroll().top + 300);
} function animate(ele, target) {
clearInterval(ele.timer);
ele.timer = setInterval(function () {
var step = (target - ele.offsetTop) / 10;
step = step > 0 ? Math.ceil(step) : Math.floor(step);
ele.style.top = ele.offsetTop + step + "px";
if (Math.abs(target - ele.offsetTop) <= Math.abs(step)) {
ele.style.top = target + "px";
clearInterval(ele.timer);
}
}, 15);
} function scroll() {
return {
"top": window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop,
"left": window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft
};
}
</script>
</body>
</html>

回到顶部

1、技术点：window.scrollTo(x,y)，之前都是移动某个元素，现在是需要移动整个显示区域，所以用window.scrollTo(x,y)

2、浏览器显示区域已经滚动的距离其实就是scrollTop值，做缓动画，只需要将这个值慢慢变小，一直到0即可。

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
} body {
height: 5000px;
} .box1 {
width: 800px;
margin: 50px auto;
font: 500 25px/45px "simsun";
color: red;
text-align: center;
} span {
position: fixed;
bottom: 30px;
right: 30px;
width: 40px;
height: 120px;
background: rgba(255, 142, 142, 0.3);
font: 600 30px/30px "simsun";
color: red;
text-align: center;
display: none;
} </style>
</head>
<body>
<span>回<br>到<br>顶<br>部</span>
<div class="box1">
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
锄禾日当午，汗滴禾下土，谁知盘中餐，粒粒皆幸苦<br>
</div>
<script>
var sp = document.getElementsByTagName("span")[0];
var target = 0;//目标位置
var leader = 0;//显示区域自身的位置
window.onscroll = function () {
if (scroll().top > 400) {
sp.style.display = "block";
} else {
sp.style.display = "none";
}
leader = scroll().top;
}
var timer = null;
sp.onclick = function () {
clearInterval(timer);
timer = setInterval(function () {
var step = (target - leader) / 10;
step = step > 0 ? Math.ceil(step) : Math.floor(step);
leader = leader + step;
window.scrollTo(0, leader);
if (Math.abs(target - leader) <= Math.abs(step)) {
window.scrollTo(0, 0);
clearInterval(timer);
} }, 15);
} function scroll() {
return {
"top": window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop,
"left": window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft
};
}
</script>
</body>
</html>

楼层跨越

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
padding: 0;
margin: 0;
list-style: none;
} body {
height: 5000px;
} ul {
width: 800px;
margin: 0 auto;
} ul li {
height: 400px;
} ol {
position: fixed;
top: 150px;
left: 350px;
} ol li {
width: 50px;
height: 50px;
font: 500 15px/50px "simsun";
text-align: center;
border: 1px solid #ccc;
margin-top: -1px;
cursor: pointer;
}
</style>
</head>
<body>
<ul>
<li>上衣</li>
<li>下衣</li>
<li>春天</li>
<li>夏衣</li>
<li>秋衣</li>
<li>冬衣</li>
</ul>
<ol>
<li>上衣</li>
<li>下衣</li>
<li>春天</li>
<li>夏衣</li>
<li>秋衣</li>
<li>冬衣</li>
</ol>
<script>
var ul = document.getElementsByTagName("ul")[0];
var uLiArr = ul.children;
var ol = document.getElementsByTagName("ol")[0];
var oLiArr = ol.children;
var arrColor = ["pink", "blue", "yellow", "orange", "green", "red"];
var timer = null;
var dispalyArea = 0;//显示区域坐标
var target = 0;//目标值
for (var i = 0; i < arrColor.length; i++) {
uLiArr[i].style.backgroundColor = arrColor[i];
oLiArr[i].style.backgroundColor = arrColor[i];
oLiArr[i].index = uLiArr[i].offsetTop;
//显示区域的scrollTop值与目标的scrollTop值差值
oLiArr[i].onclick = function () {
target = this.index;
clearInterval(timer);
timer = setInterval(function () {
var step = (target - dispalyArea) / 10;
step = step > 0 ? Math.ceil(step) : Math.floor(step);
dispalyArea = dispalyArea + step;
window.scrollTo(0, dispalyArea);
if (Math.abs(target - dispalyArea) <= Math.abs(step)) {
clearInterval(timer);
window.scrollTo(0, target);
}
}, 15);
}
}
window.onscroll = function () {
dispalyArea = scroll().top;
} function scroll() {
return {
"top": window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop,
"left": window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft
};
}
</script>
</body>
</html>