弹性运动公式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
#box{
width: 100px;
height: 30px;
background: orange;
}
</style>
</head>
<body>
<div id='box'>
</div>
<script type="text/javascript">
(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'] || // Webkit中此取消方法的名字变了
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);
};
}
}());
//以上requestAnimationFrame兼容处理
var oBox = document.getElementById('box');
var oBoxwidth = oBox.clientWidth;
function move(obj,str,end){
var timer,
nowWidth = str,
overWidth = end;
obj.speed = 0
cancelAnimationFrame(timer)
timer = requestAnimationFrame(function fn(){
obj.speed += (overWidth-nowWidth)/6; //6为系数
obj.speed *=0.75; //0.75摩擦系数
nowWidth+=obj.speed
obj.style.width = nowWidth+'px'
if(Math.abs(overWidth-nowWidth)<=1 && obj.speed<=1){
obj.style.width = end+'px' // 校 正
cancelAnimationFrame(timer)
}else{
requestAnimationFrame(fn)
}
})
}
oBox.onmouseover = function(){
move(this,oBoxwidth,300)
}
oBox.onmouseout = function(){
move(this,300,oBoxwidth)
}
</script>
</body>
</html>
