监听 scroll 计算
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
* {
padding: 0;
margin: 0;
}
.container {
width: 100vw;
height: 100vh;
box-sizing: border-box;
padding: 48px 0 50px;
}
.header {
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 48px;
background-color: pink;
}
.footer {
position: fixed;
width: 100%;
height: 50px;
left: 0;
bottom: 0;
background-color: pink;
}
.content {
position: relative;
height: 100%;
overflow-y: scroll;
box-sizing: border-box;
}
/* section h2 {
position: sticky;
top: 0;
background-color: lightyellow;
} */
section {
position: relative;
box-sizing: border-box;
padding-top: 40px;
}
section h2 {
display: flex;
justify-content: center;
align-items: center;
position: absolute;
left: 0;
top: 0;
width: 100%;
height: 40px;
background-color: lightyellow;
}
section h2.sticky {
position: fixed;
top: 48px;
}
</style>
</head>
<body>
<div class="container">
<div class="header"></div>
<div class="content">
<section>
<h2>HEADER1</h2>
<div class="desc">
...
</div>
</section>
<section>
<h2>HEADER2</h2>
<div class="desc">
...
</div>
</section>
<section>
<h2>HEADER3</h2>
<div class="desc">
...
</div>
</section>
</div>
<div class="footer"></div>
</div>
<script>
const oContent = document.getElementsByClassName("content")[0];
const oH2List = document.getElementsByTagName("h2");
const offsetTopList = [];
[...oH2List].forEach((ele) => {
offsetTopList.push({
offsetTop: ele.parentElement.offsetTop,
clientHeight: ele.parentElement.clientHeight,
});
});
oContent.onscroll = function (e) {
offsetTopList.forEach((v, idx) => {
if (
oContent.scrollTop > v.offsetTop &&
oContent.scrollTop < v.clientHeight + v.offsetTop
) {
oH2List[idx].classList.add("sticky");
} else {
oH2List[idx].classList.remove("sticky");
}
});
};
</script>
</body>
</html>
position: sticky
boxTop {
position: sticky;
top: 0;
}
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