效果图

示例


<html>
<head>
<title>自动播放——幻灯片缓冲效果</title>
<style> 
body,div,ul,li{margin:0;padding:0;}
ul{list-style-type:none;}
body{background:#000;text-align:center;font:12px/20px Arial;}
#box{position:relative;width:492px;height:172px;background:#fff;border-radius:5px;border:8px solid #fff;margin:10px auto;cursor:pointer;}
#box .list{position:relative;width:490px;height:170px;overflow:hidden;}
#box .list ul{position:absolute;top:0;left:0;}
#box .list li{width:490px;height:170px;overflow:hidden;}
#box .count{position:absolute;right:0;bottom:5px;}
#box .count li{color:#fff;float:left;width:20px;height:20px;cursor:pointer;margin-right:5px;overflow:hidden;background:#F90;opacity:0.7;filter:alpha(opacity=70);border-radius:20px;}
#box .count li.current{color:#fff;opacity:1;filter:alpha(opacity=100);font-weight:700;background:#f60;}
#tmp{width:100px;height:100px;background:red;position:absolute;}
</style>
<script type="text/javascript"> 
window.onload = function ()
{var oBox = document.getElementById("box");var oList = oBox.getElementsByTagName("ul")[0];var aImg = oBox.getElementsByTagName("img");var timer = playTimer = null;var index = i = 0;var bOrder = true;var aTmp = [];//生成数字按钮for (i = 0; i < aImg.length; i++){aTmp.push("<li>" + (i + 1) + "</li>")}//插入元素var oCount = document.createElement("ul");oCount.className = "count"oCount.innerHTML = aTmp.join("");oBox.appendChild(oCount);//初始化状态var aBtn = oBox.getElementsByTagName("ul")[1].getElementsByTagName("li");aBtn[index].className = "current";//按钮点击切换for (i = 0; i < aBtn.length; i++){aBtn[i].index = i;aBtn[i].onclick = function (){index = this.index;for (i = 0; i < aBtn.length; i++) aBtn[i].className = "";this.className = "current";			startMove(-(this.index * aImg[0].offsetHeight))		}}//鼠标移入展示区停止自动播放oBox.onmouseover = function (){clearInterval(playTimer)};//鼠标离开展示区开始自动播放oBox.onmouseout = function (){autoPlay()};//页面加载即调用自动播放oBox.onmouseout();//自动播放函数function autoPlay(){playTimer = setInterval(function (){bOrder ? index++ : index--;			index == aBtn.length - 1 && (bOrder = false);index == 0 && (bOrder = true);aBtn[index].onclick();startMove(-(index * aImg[0].offsetHeight))}, 3000)}function startMove(iTarget){clearInterval(timer);timer = setInterval(function (){doMove(iTarget)}, 30)	}function doMove (iTarget){var iSpeed = (iTarget - oList.offsetTop) / 10;iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);		oList.offsetTop == iTarget ? clearInterval(timer) : oList.style.top = oList.offsetTop + iSpeed + "px"}
};
</script>
</head>
<body>
<div id="box"><div class="list"><ul><li><img src="wall5.jpg" width="490" height="170" /></li><li><img src="wall6.jpg" width="490" height="170" /></li><li><img src="wall7.jpg" width="490" height="170" /></li></ul></div>
</div>
</body>
</html>