<!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>
</head>
<style>
div {
width: 300px;
height: 800px;
background: linear-gradient(#FFF, #f45, #f67);
}
button {
position: fixed;
bottom: 10px;
}
</style>
<body>
<div>
<button id="but">回到顶部</button>
</div>
<script>
document.getElementById('but').onclick = function () {
document.body.scrollTop = 0;
document.documentElement.scrollTop = 0;
}
</script>
</body>
</html>
