<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>JS多物体动画</title>
<style type="text/css">
{margin: 0;padding: 0;}
ul,li{
list-style: none;
}
ul li{
width: 200px;
height: 100px;
background: yellow;
margin-bottom: 20px;
border: 4px solid #000;
filter: alpha(opacity:30);
opacity: 0.3;
}
</style>
<script type="text/javascript">
/JS多物体动画：实现多物体运动的关键点：<1>获取到每个元素<2>给每个元素绑定上事件<3>注意使用this区分当前操作的元素<4>定时器不能只设定一个了，应该给每个元素分配一个定时器，避免多个元素抢同一个定时器造成宽度一样的bug（注意：多物体运动不能共同用一个东西（某一参数，比如定时器）/
window.onload=function(){
var li1=document.getElementById('li1'),
li2=document.getElementById('li2');
li1.onmouseover=function(){
//startMove(this,'height',400);
startMove(this,'opacity',100);
};
li1.onmouseout=function(){
//startMove(this,'height',100);
startMove(this,'opacity',30);
};
/ li2.onmouseover=function(){
startMove(this,'width',400);
};
li2.onmouseout=function(){
startMove(this,'width',200);
};*/
};
//获取属性值
function getStyle(obj,attr){
if(obj.currentStyle){
//兼容IE浏览器
return obj.currentStyle[attr];
}else{
//兼容firefox浏览器
return getComputedStyle(obj,false)[attr];
}
}
//var timer=null;
var alpha=30;
function startMove(obj,attr,iTarget){
//清除定时器
clearInterval(obj.timer);
//设置定时器
obj.timer=setInterval(function(){
var icur=0;
if (attr=='opacity') {
icur=Math.round(parseFloat(getStyle(obj,attr))*100);
} else {
icur=parseInt(getStyle(obj,attr));
}
var speed=(iTarget-icur)/8;
speed=speed>0?Math.ceil(speed):Math.floor(speed);
if(icur==iTarget){
clearInterval(obj.timer);
}else{
if (attr=='opacity') {
obj.style.filter='alpha(opacity:'+(icur+speed)+')';
obj.style.opacity=(icur+speed)/100;
} else {
obj.style[attr]=icur+speed+'px';
}
}
},30);
}
</script>
</head>
<body>
<ul>
<li id="li1"></li>
<!-- <li id="li2"></li> -->
</ul>
</body>
</html>
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