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這篇文章主要講解了“JS怎么使用window.requestAnimationFrame()實現逐幀動畫”，文中的講解內容簡單清晰，易于學習與理解，下面請大家跟著小編的思路慢慢深入，一起來研究和學習“JS怎么使用window.requestAnimationFrame()實現逐幀動畫”吧！
window.requestAnimationFrame() 方法告訴瀏覽器您希望執行動畫，并請求瀏覽器調用指定的函數在下一次重繪之前更新動畫。該方法使用一個回調函數作為參數，這個回調函數會在瀏覽器重繪之前調用。
如果你想做逐幀動畫的時候，你應該用這個方法。這就要求你的動畫函數執行會先于瀏覽器重繪動作。通常來說，被調用的頻率是每秒60次，但是一般會遵循W3C標準規定的頻率。如果是后臺標簽頁面，重繪頻率則會大大降低。
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
瀏覽器支持情況:
下面通過兩個簡單的Demo介紹下window.requestAnimationFrame() 方法的使用
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>返回頂部</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><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>錨點定位</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')">跳到第一個</div>
<div class="top top2" onclick="goPosition('box2')">跳到第二個</div>
<div class="top top3" onclick="goPosition('box3')">跳到第三個</div>
<div class="top top4" onclick="goPosition('box4')">跳到第四個</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>// 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 M?ller. 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);
};
}());感謝各位的閱讀，以上就是“JS怎么使用window.requestAnimationFrame()實現逐幀動畫”的內容了，經過本文的學習后，相信大家對JS怎么使用window.requestAnimationFrame()實現逐幀動畫這一問題有了更深刻的體會，具體使用情況還需要大家實踐驗證。這里是億速云，小編將為大家推送更多相關知識點的文章，歡迎關注！
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