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ckgd2/任务1和任务2.html

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2.0 KiB

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="header">
我是头部
</div>
<div class="main">
<div class="content">
秒杀模块
</div>
</div>
<!--回到顶部按钮-->
<div id="toTop" style="position: fixed; bottom: 70px; right: 50px; border-radius: 50%; background-color: rgba(0,0,0,0.1); height: 30px;width: 30px; display: none;flex-direction: column; justify-content: center; align-items: center;">
<img src="./assets/top.png" style="height: 20px; width: 20px;" alt="">
</div>
</body>
<style>
.header{
position: fixed;
top: -80px;
left: 0;
width: 100%;
height: 80px;
background-color: skyblue;
text-align: center;
color: #fff;
line-height: 80px;
font-size: 30px;
transition: all 0.3s;
}
.main{
height: 1800px;
width: 1000px;
background-color: pink;
}
.content{
position: absolute;
top: 500px;
background-color: gray;
}
</style>
<script>
const content = document.querySelector('.content')
const header = document.querySelector('.header')
const toTop = document.querySelector('#toTop')
window.addEventListener('scroll',function(){
const n = document.documentElement.scrollTop
let viewScrollTop = document.documentElement.scrollTop
if(n>=content.offsetTop){
header.style.top = 0
}else{
header.style.top = '-80px'
}
if(viewScrollTop>400){
toTop.style.display = 'flex'
}else{
toTop.style.display = 'none'
}
})
toTop.addEventListener('click',()=>{
document.documentElement.scrollTop = 0
})
</script>
</html>