带Loading效果的图片切换_图片特效

带Loading效果的图片切换: 发布时间：2020-01-24编辑：脚本学堂

带Loading效果的图片切换，新闻门户类网站较常用的图片切换风格，JS技术实现。

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>带Loading效果的图片切换</title>
<style type="text/css"> 
body,div,ul,li{margin:0;padding:0;}
li{list-style:none;}
body{font:12px/1.5 5fae8f6f96c59ed1;background:#000;}
#big{position:relative;width:800px;height:auto!important;height:400px;min-height:400px;margin:20px auto;text-align:center;}
#title{position:absolute;top:0;left:0;width:100%;background:#000;color:#fff;opacity:0.7;filter:alpha(opacity=70);font-size:20px;height:50px;}
#title span{padding:0 5px;<a href=http://www.jb200.com/article/15092.html target=_blank class=infotextkey>line-height</a>:50px;display:block;}
#big.loading{background:url(/source/images/201207/loading.gif) 50% 50% no-repeat;}
#masks_L,#masks_R{position:absolute;top:0;width:400px;height:100%;cursor:pointer;background:#f0f0f0;opacity:0;filter:alpha(opacity=0);}
#masks_L{left:0;}
#masks_R{right:0;}
#btn_L,#btn_R{position:absolute;top:50%;margin-top:-40px;width:39px;height:80px;overflow:hidden;cursor:pointer;text-indent:-9999px;background:url(/source/images/201207/btn.png) no-repeat;opacity:0;filter:alpha(opacity=0);}
#btn_L{left:10px;background-position:0 0;}
#btn_R{right:10px;background-position:-39px 0;}
</style>
<script type="text/<a href=http://www.jb200.com/js/ target=_blank class=infotextkey>javascript</a>"> 
function getStyle(obj, attr){return obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj, null)[attr]}
window.onload = function ()
{
	var oBig = document.getElementById("big");
	var oMasksL = document.getElementById("masks_L");
	var oMasksR = document.getElementById("masks_R");
	var oBtnL = document.getElementById("btn_L");
	var oBtnR = document.getElementById("btn_R");
	var oTitle = document.getElementById("title");
	var oSpan = oTitle.getElementsByTagName("span")[0];
	var iNow = 0;
	var aData = [
		{"imgSrc" : "/source/images/201207/53706421.jpg", "title" : "7月26日，吊车将事故现场的车头残片吊至大型运输车辆上。"},
		{"imgSrc" : "/source/images/201207/53706420.jpg", "title" : "7月26日，一辆大卡车准备驶离事故现场。"},
		{"imgSrc" : "/source/images/201207/53706416.jpg", "title" : "7月26日，工人在给最后一节车厢盖上彩条布，准备运离现场。"},
		{"imgSrc" : "/source/images/201207/53706414.jpg", "title" : "7月26日，一名工人在事故现场最后一节车厢上作业。"},
		{"imgSrc" : "/source/images/201207/53706415.jpg", "title" : "7月26日，工人在给最后一节车厢盖上彩条布，准备运离现场。"}
	];
	
	oMasksL.onmouseover = oBtnL.onmouseover = function ()
	{
		startMove(oBtnL, "opacity", 100)
	};
	oMasksL.onmouseout = oBtnL.onmouseout = function ()
	{
		startMove(oBtnL, "opacity", 0)	
	};
	
	oMasksR.onmouseover = oBtnR.onmouseover = function ()
	{
		startMove(oBtnR, "opacity", 100)
	};
	oMasksR.onmouseout = oBtnR.onmouseout = function ()
	{
		startMove(oBtnR, "opacity", 0)	
	};
	
	function startMove(obj, attr, iTarget, fnEnd)
	{
		clearInterval(obj.timer);
		obj.timer = setInterval(function ()
		{
			doMove(obj, attr, iTarget, fnEnd)
		}, 30)	
	}
	
	function doMove(obj, attr, iTarget, fnEnd)
	{
		var iCur = parseFloat(getStyle(obj, attr));
		if (attr == "opacity")
		{
			iCur = parseInt(iCur * 100)
		}
		var iSpeed = (iTarget - iCur) / 5;
		iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
		
		if (iTarget == iCur)
		{
			clearInterval(obj.timer);
			fnEnd && fnEnd();	
		}
		else
		{
			if (attr == "opacity")
			{
				obj.style.filter = "alpha(opacity = " + (iCur + iSpeed) + ")";
				obj.style.opacity = (iCur + iSpeed)	/ 100;
			}
			else
			{
				obj.style[attr] = iCur + iSpeed + "px";	
			}
		}
	}
	
	oBtnL.onclick = function ()
	{
		
		if (iNow <= 0)
		{
			alert("前面没有图片了！")
			return;
		}
		iNow--;
		loadImg();
	};
	
	oBtnR.onclick = function ()
	{
		if(iNow >= aData.length - 1)
		{
			alert("这是最后一张图片了！")
			return;
		}
		iNow++;
		loadImg();
	};
	
	loadImg();
	function loadImg()
	{
		oBig.className = "loading";
		oSpan.style.opacity = oTitle.style.height = 0;
		oSpan.style.filter = "alpha(opacity=0)";
		var oImg = oBig.getElementsByTagName("img");
		oImg[0] && oBig.removeChild(oImg[0]);
		var oTemp = document.createElement("img");
		var oNewImg = new Image();
		oNewImg.onload = function ()
		{
			oBig.className = "";			
			oTemp.src = this.src;
			oBig.appendChild(oTemp);
			oTemp.style.width = (oTemp.offsetWidth > 800 ? 800 : oTemp.offsetWidth) + "px";
			oBig.style.height = oTemp.style.height = oTemp.offsetHeight * oTemp.offsetWidth / oTemp.offsetWidth + "px";
			oSpan.innerHTML = aData[iNow].title;
			startMove(oTitle, "height", 50, function (){
				startMove(oTitle.childNodes[0], "opacity", 100)	
			})
		};
		oNewImg.src = aData[iNow].imgSrc
	}
};
</script>
</head>
<body>
	<div id="big">
    	<div id="masks_L"></div>
    	<div id="masks_R"></div>
        <div id="btn_L">左</div>
        <div id="btn_R">右</div>
        <div id="title"><span></span></div>
    </div>
</body>
</html>

提示：可修改代码后再运行!

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