<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>8 任意值属性 透明度</title>
<style>
body,div{
padding:0;
margin:0;
}
#div1{
width:200px;
height:200px;
background-color:yellow;
border:4px solid #000;
opacity: 0.3;
}
</style>
<script>
window.onload=function(){
var oDiv = document.getElementById('div1');
oDiv.onmousemove = function(){
startMove(oDiv,'opacity',100);
};
oDiv.onmouseout = function(){
startMove(oDiv,'opacity',30);
}
};
function startMove(obj,attr,iTarget){
clearInterval(obj.timer);
obj.timer = setInterval(function(){
var icur = null; //属性值 变量
if(attr == 'opacity'){
icur = Math.round(parseFloat(getStyle(obj,attr))*100);
}else{
icur = parseInt(getStyle(obj,attr));
}
var speed = (iTarget - icur)/8; // 速度 变速
speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed);
if(icur == iTarget){ //变量变化
clearInterval(obj.timer);
}else{
if(attr == 'opacity'){
obj.style.opacity = (icur + speed)/100;
}else{
obj.style[attr] = icur + speed + 'px';
}
}
},30)
}
function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}
else{
return getComputedStyle(obj,false)[attr];
}
}
</script>
</head>
<body>
<div id="div1"></div>
</body>
</html>
