<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.but {
position: fixed;
bottom: 0px;
right: 0px;
}
</style>
<style>
body {
height: 30000px;
}
</style>
</head>
<body>
<button class="but" id="btn">回到顶部</button>
<script>
window.onscroll = function () {
console.log(document.documentElement.scrollTop || document.body.scrollTop)
if ((document.documentElement.scrollTop || document.body.scrollTop) > 0) {
document.getElementById("btn").style.display = "block";
} else {
document.getElementById("btn").style.display = "none";
}
}
btn.onclick = function () {
window.scrollTo({
left: 0,
top: 0
})
}
</script>
</body>
</html>
