javascript运动框架用法实例分析(实现放大与缩小效果)
2016-01-09 09:35作者：fang
本文实例讲述了javascript运动框架用法。分享给大家供大家参考，具体如下：
该运动框架可以实现多物体任意值运动
运行效果截图如下：
例子：
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>运动框架</title>
<style>
#div1{ width:100px; height:100px; background:red; position:absolute; left:0; top:50px; opacity:0.3; filter:alpha(opacity=30);}
</style>
<script>
window.onload = function()
{
var oBtn = document.getElementById('btn1');
var oDiv = document.getElementById('div1');
oBtn.onclick = function()
{
startMove(oDiv, {width:200, height:200, opacity:100}, function(){
startMove(oDiv, {width:100, height:100, opacity:30});
});
};
};
function getStyle(obj, attr)
{
if(obj.currentStyle){
return obj.currentStyle[attr];
}else{
return getComputedStyle(obj, false)[attr];
}
}
function startMove(obj, json, fn)
{
clearInterval(obj.timer);
obj.timer = setInterval(function(){
var bStop = true;
for(var attr in json){
var iCur = 0;
if(attr == 'opacity'){
iCur = Math.round(parseFloat(getStyle(obj, attr))*100);
}else{
iCur = parseInt(getStyle(obj, attr));
}
var iSpeed = (json[attr] - iCur)/8;
iSpeed = iSpeed>0?Math.ceil(iSpeed):Math.floor(iSpeed);
if(iCur != json[attr]){
bStop = false;
}
if(attr == 'opacity'){
obj.style.filter = 'alpha(opacity='+(iCur+iSpeed)+')';
obj.style.opacity = (iCur+iSpeed)/100;
}else{
obj.style[attr] = iCur + iSpeed + 'px';
}
}
if(bStop){
clearInterval(obj.timer);
if(fn){
fn();
}
}
}, 30);
}
</script>
</head>
<body>
<input id="btn1" type="button" value="运动"/>
<div id="div1"></div>
</body>
</html>
希望本文所述对大家JavaScript程序设计有所帮助。