本文实例讲述了javascript实现的左右无缝滚动效果。分享给大家供大家参考，具体如下：
今天介绍的是几张图片一起进行无缝滚动，这是一个常用的 js 效果。
<!DOCTYPE HTML>
<html>
<head>
<meta charset="UTF-8">
<title>无缝滚动——左右</title>
<link rel="stylesheet" type="text/css" href="../css/base.css" media="all"/>
<style type="text/css">
#scroll{width:698px;height:108px;margin:50px auto 0;position:relative;overflow:hidden;}
.btn_left{display:block;width:68px;height:68px;background:url(images/btn.jpg) no-repeat -70px -69px;position:absolute;top:20px;left:1px;z-index:1;}
.btn_left:hover{background:url(images/btn.jpg) no-repeat -70px 0;}
.btn_right{display:block;width:68px;height:68px;background:url(images/btn.jpg) no-repeat 1px -69px;position:absolute;top:20px;right:0;z-index:1;}
.btn_right:hover{background:url(images/btn.jpg) no-repeat 1px 0;}
#scroll .content{width:546px;height:108px;position:relative;overflow:hidden;margin:0 auto;}
#scroll ul{position:absolute;}
#scroll li{float:left;width:182px;height:108px;text-align:center;}
#scroll li a:hover{position:relative;top:2px;}
</style>
</head>
<body>
<p id="scroll">
<a href="javascript:;"></a>
<a href="javascript:;"></a>
<p>
<ul>
<li><a href="#"><img src="images/1.jpg" width="178" height="108" alt=""/></a></li>
<li><a href="#"><img src="images/2.jpg" width="178" height="108" alt=""/></a></li>
<li><a href="#"><img src="images/3.jpg" width="178" height="108" alt=""/></a></li>
<li><a href="#"><img src="images/4.jpg" width="178" height="108" alt=""/></a></li>
</ul>
</p>
</p>
</body>
</html>
<script type="text/javascript">
window.onload = function(){
var oDiv = document.getElementById('scroll');
var oUl = oDiv.getElementsByTagName('ul')[0];
var aLi = oDiv.getElementsByTagName('li');
var aBtn = oDiv.getElementsByTagName('a');
var speed = -1;
var timer = null;
oUl.innerHTML += oUl.innerHTML;
oUl.style.width = aLi[0].offsetWidth * aLi.length + 'px';
timer = setInterval(function(){
oUl.style.left = oUl.offsetLeft + speed + 'px';
if(oUl.offsetLeft < - oUl.offsetWidth / 2){
oUl.style.left = '0';
}else if(oUl.offsetLeft > 0){
oUl.style.left = - oUl.offsetWidth / 2 + 'px';
}
},30);
aBtn[0].onclick = function(){
speed = -1;
};
aBtn[1].onclick = function(){
speed = 1;
};
oUl.onmouseover = function(){
clearInterval(timer);
};
oUl.onmouseout = function(){
timer = setInterval(function(){
oUl.style.left = oUl.offsetLeft + speed + 'px';
if(oUl.offsetLeft < -oUl.offsetWidth / 2){
oUl.style.left = '0';
}else if(oUl.offsetLeft > 0){
oUl.style.left = - oUl.offsetWidth / 2 + 'px';
}
},30);
};
};
</script>PS：如果想要改变移动速度，只需要改变 speed 的值。
希望本文所述对大家JavaScript程序设计有所帮助。
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