<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>返回顶部</title>
<script src="jqsourse.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
body {
height: 4000px;
}
div {
100px;
height: 30px;
position: fixed;
right: 50px;
bottom: 50px;
background-color: red;
color: white;
line-height: 30px;
text-align: center;
display: none; /*默认不可见 如果轮下去大于300那么就让他可见*/
}
</style>
</head>
<body>
<div>返回顶部</div>
</body>
<script>
//点击返回顶部时开始返回 时间一秒 匀速
$('div').click(() => {
$('html').animate({
scrollTop: 0
}, 1000, 'linear', () => {
console.log("yes");
})
});
//鼠标滚轮时 停止运动
$('html').on('wheel', () => {
$('html').stop();
});
//判断滚轮是否大于 300 如果就显示 否则不显示
setInterval(()=>{
let leng = $('html').scrollTop();
if(leng > 300){
$('div').css('display','block');
}else{
$('div').css('display','none');
}
},10);
</script>
</html>