一、场景
当你要完成一个返回顶部的功用时刻你会怎么做，大部分人会运用document.body.scrollTop =0；这么写就完成了功用，不过要越发的细致一点我们无妨用tween的缓动来完成，看看结果怎样吧。
之前我们写过tween的相干文章，这里不做引见了。
二、代码
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script src="https://cdn.jsdelivr.net/npm/vue"></script>
<style type="text/css">
#app{width: 100%; height: 3000px;background: #CCCCCC;}
.backTop{
width: 1.5rem;
height: 1.5rem;
border: 1px solid #ff0000;
position: fixed;
right: 1rem;
bottom: 2rem;
border-radius: 50%;
/*background: url(/static/imgs/backtop20180226.png) no-repeat 40%;*/
background-size: 70% 100%;
}
</style>
</head>
<body>
<div id="app">
<div @click="backTop()" class="backTop">Top</div>
</div>
<script type="text/javascript">
var app = new Vue({
el:"#app",
data:{
},
methods:{
backTop(){
// * t: current time（当前时候）；
// * b: beginning value（初始值）；
// * c: change in value（变化量）；
// * d: duration（持续时候）。
var Tween = {
Linear: function(t, b, c, d) { //匀速运动，想要完成其他的结果能够运用tween的其他要领
return c * t / d + b;
}
}
Math.tween = Tween;
var t = 1;
const b = document.documentElement.scrollTop;
const c = 50;
const d = 5;
const setInt = setInterval(()=>{
t--;
console.log(t)
if(document.documentElement.scrollTop == 0){clearInterval(setInt)}
console.log(t);
const backTop = Tween.Linear(t,b,c,d);
console.log(backTop);
document.documentElement.scrollTop = backTop;
},20)
}
}
})
</script>
</body>
</html>
三、requestAnimationFrame改写setInterval要领：
methods:{
backTop(){
var Tween = {
Linear: function(t, b, c, d) { //匀速
return c * t / d + b;
}
}
Math.tween = Tween;
var t = 1;
const b = document.body.scrollTop;
const c = 1;
const d = 1;
var timer;
timer= requestAnimationFrame(function fn(){
if(document.body.scrollTop > 0){
t--;
console.log(t)
console.log(t);
const backTop = Tween.Linear(t,b,c,d);
console.log(backTop);
document.body.scrollTop = backTop;
timer = requestAnimationFrame(fn);
}else{
cancelAnimationFrame(timer)
}
})
}
}jquery
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script src="https://cdn.jsdelivr.net/npm/vue"></script>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>
<style type="text/css">
#app {
width: 100%;
height: 3000px;
background: #CCCCCC;
}
.backTop {
width: 1.5rem;
height: 1.5rem;
border: 1px solid #ff0000;
position: fixed;
right: 1rem;
bottom: 2rem;
border-radius: 50%;
/*background: url(/static/imgs/backtop20180226.png) no-repeat 40%;*/
background-size: 70% 100%;
}
</style>
</head>
<body>
<div id="app">
<div class="backTop">Top</div>
</div>
<script type="text/javascript">
$(".backTop").click(function() {
console.log(11)
var Tween = {
Linear: function(t, b, c, d) { //匀速运动，想要完成其他的结果能够运用tween的其他要领
return c * t / d + b;
}
}
Math.tween = Tween;
var t = 1;
const b = document.documentElement.scrollTop;
const c = 50;
const d = 5;
const setInt = setInterval(() => {
t--;
console.log(t)
if(document.documentElement.scrollTop == 0) {
clearInterval(setInt)
}
console.log(t);
const backTop = Tween.Linear(t, b, c, d);
console.log(backTop);
document.documentElement.scrollTop = backTop;
}, 20)
})
</script>
</body>
</html>四、相干链接
https://www.cnblogs.com/qiand…
https://www.jianshu.com/p/b77…
