window.requestanimationframe() 方法告诉浏览器您希望执行动画，并请求浏览器调用指定的函数在下一次重绘之前更新动画。该方法使用一个回调函数作为参数，这个回调函数会在浏览器重绘之前调用。
如果你想做逐帧动画的时候，你应该用这个方法。这就要求你的动画函数执行会先于浏览器重绘动作。通常来说，被调用的频率是每秒60次，但是一般会遵循w3c标准规定的频率。如果是后台标签页面，重绘频率则会大大降低。
基本语法:
requestid = window.requestanimationframe(callback); // firefox 23 / ie10 / chrome / safari 7 (incl. ios) requestid = window.mozrequestanimationframe(callback); // firefox < 23 requestid = window.webkitrequestanimationframe(callback); // older versions chrome/webkit
浏览器支持情况:
下面通过两个简单的demo介绍下window.requestanimationframe() 方法的使用
返回顶部
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>返回顶部</title>
<style>
.box {
margin: 0 auto;
width: 100%;
height: 5000px;
}
.box1 {
background: #b94a48;
}
.box2 {
background: #fb8c00;
}
.box3 {
background: #669900;
}
.box4 {
background: #c0a16b;
}
.top {
position: fixed;
right: 20px;
bottom: 20px;
width: 40px;
height: 40px;
background: #8dc7ff;
border-radius: 50%;
cursor: pointer;
}
</style>
<script>
window.requestanimationframe = (function () {
return window.requestanimationframe ||
window.webkitrequestanimationframe ||
window.mozrequestanimationframe ||
function (callback) {
window.settimeout(callback, 6000 / 60)
}
})()
window.cancelanimframe = (function () {
return window.cancelanimationframe ||
window.webkitcancelanimationframe ||
window.mozcancelanimationframe ||
window.ocancelanimationframe ||
window.mscancelanimationframe ||
function (callback) {
window.cleartimeout(callback)
}
})()
function scrolltotop() {
let top = window.pageyoffset
const duration = 320
const step = top / (duration / (1000 / 60)) >> 0
const fn = () => {
if (top >= 0) {
top -= step
window.scrollto(0, top)
fn.raftimer = window.requestanimationframe(fn)
} else {
window.scrollto(0, 0)
window.cancelanimationframe(fn.raftimer)
}
}
fn.raftimer = window.requestanimationframe(fn)
}
</script>
</head>
<body>
<div class="box box1"></div>
<div class="box box2"></div>
<div class="box box3"></div>
<div class="box box4"></div>
<div class="top" onclick="scrolltotop()"></div>
</body>
</html>
锚点定位
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>锚点定位</title>
<style>
.top {
margin: 100px auto;
cursor: pointer;
}
.top1 {
color: #b94a48;
}
.top2 {
color: #fb8c00;
}
.top3 {
color: #669900;
}
.top4 {
color: #c0a16b;
}
.box {
margin: 0 auto;
width: 100%;
height: 5000px;
}
.box1 {
background: #b94a48;
}
.box2 {
background: #fb8c00;
}
.box3 {
background: #669900;
}
.box4 {
background: #c0a16b;
}
</style>
<script>
window.requestanimationframe = (function () {
return window.requestanimationframe ||
window.webkitrequestanimationframe ||
window.mozrequestanimationframe ||
function (callback) {
window.settimeout(callback, 6000 / 60)
}
})()
window.cancelanimframe = (function () {
return window.cancelanimationframe ||
window.webkitcancelanimationframe ||
window.mozcancelanimationframe ||
window.ocancelanimationframe ||
window.mscancelanimationframe ||
function (callback) {
window.cleartimeout(callback)
}
})()
function goposition(index) {
let top = 0
let distance = document.getelementbyid(index).offsettop
const duration = 320
const step = distance / (duration / (1000 / 60)) >> 0
const fn = () => {
if (distance >= top) {
top += step
window.scrollto(0, top)
fn.raftimer = window.requestanimationframe(fn)
} else {
window.cancelanimationframe(fn.raftimer)
}
}
fn.raftimer = window.requestanimationframe(fn)
}
</script>
</head>
<body>
<div class="top top1" onclick="goposition('box1')">跳到第一个</div>
<div class="top top2" onclick="goposition('box2')">跳到第二个</div>
<div class="top top3" onclick="goposition('box3')">跳到第三个</div>
<div class="top top4" onclick="goposition('box4')">跳到第四个</div>
<div id="box1" class="box box1"></div>
<div id="box2" class="box box2"></div>
<div id="box3" class="box box3"></div>
<div id="box4" class="box box4"></div>
</body>
</html>
网上技术大牛针对浏览器兼容封装源码:
// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
// requestanimationframe polyfill by erik möller. fixes from paul irish and tino zijdel
// mit license
(function() {
var lasttime = 0;
var vendors = ['ms', 'moz', 'webkit', 'o'];
for(var x = 0; x < vendors.length && !window.requestanimationframe; ++x) {
window.requestanimationframe = window[vendors[x]+'requestanimationframe'];
window.cancelanimationframe = window[vendors[x]+'cancelanimationframe']
|| window[vendors[x]+'cancelrequestanimationframe'];
}
if (!window.requestanimationframe)
window.requestanimationframe = function(callback, element) {
var currtime = new date().gettime();
var timetocall = math.max(0, 16 - (currtime - lasttime));
var id = window.settimeout(function() { callback(currtime + timetocall); },
timetocall);
lasttime = currtime + timetocall;
return id;
};
if (!window.cancelanimationframe)
window.cancelanimationframe = function(id) {
cleartimeout(id);
};
}());
到此这篇关于js使用window.requestanimationframe()实现逐帧动画的文章就介绍到这了。希望对大家的学习有所帮助，也希望大家多多支持。
