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转自：https://www.zhangxinxu.com/wordpress/2017/01/share-a-animation-algorithm-js/
//代码核心
Math.easeout = function (A, B, rate, callback) {
if (A == B || typeof A != 'number') {
return;
}
B = B || 0;
rate = rate || 2;
var step = function () {
A = A + (B - A) / rate;
if (A < 1) {
callback(B, true);
return;
}
callback(A, false);
requestAnimationFrame(step);
};
step();
};
//按钮btnEaseout的点击事件
document.getElementById('btnEaseout').onclick = function () {
var doc = document.body.scrollTop? document.body : document.documentElement;
Math.easeout(doc.scrollTop, 0, 6, function (value) {
doc.scrollTop = value;
});
}
低版本浏览器需要兼容requestAnimationFrame处理
if (!window.requestAnimationFrame) {
requestAnimationFrame = function(fn) {
setTimeout(fn, 17);
};
}
或者使用比较完善的兼容处理requestAnimationFrame.js：
/*! requestAnimationFrame.js
* by zhangxinxu 2013-09-30
*/
(function() {
var lastTime = 0;
var vendors = ['webkit', 'moz'];
for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] || // name has changed in Webkit
window[vendors[x] + 'CancelRequestAnimationFrame'];
}
if (!window.requestAnimationFrame) {
window.requestAnimationFrame = function(callback, element) {
var currTime = new Date().getTime();
var timeToCall = Math.max(0, 16.7 - (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);
};
}
}());
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转播
