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                        /前端開發(fā)
                        
                            /JavaScript
                        
                        /焦點(diǎn)圖輪播特效

為什么箭頭切換沒效果

<!DOCTYPE html>
<html>
<head>
? <meta charset="utf-8">
? <title>輪播圖</title>
? <style type="text/css">
??? *{ margin: 0; padding: 0; text-decoration: none;}
?? ?body { padding: 20px;}
?? ?#container { width: 520px; height: 280px; border: 3px solid #333; overflow: hidden; position: relative;}
?? ?#list { width:3640px; height: 280px; position: absolute; z-index: 1;}
?? ?#list img { float: left;width:520px;height:280px;}
?? ?#buttons { position: absolute; height: 10px; width: 100px; z-index: 2; bottom: 20px; left: 210px;}
?? ?#buttons span { cursor: pointer; float: left; border: 1px solid #fff; width: 10px; height: 10px; border-radius: 50%; background: #333; margin-right: 5px;}
?? ?#buttons .on {? background: orangered;}
?? ?.arrow { cursor: pointer; display: none; line-height: 39px; text-align: center; font-size: 36px; font-weight: bold; width: 40px; height: 40px;? position: absolute; z-index: 2; top: 120px; background-color: RGBA(0,0,0,.3); color: #fff;}
?? ?.arrow:hover { background-color: RGBA(0,0,0,.7);}
?? ?#container:hover .arrow { display: block;}
?? ?#prev { left: 20px;}
?? ?#next { right: 20px;}
? </style>
? <script type="text.javascript">
??? window.onload=function(){
?? ?? var container = document.getElementById('container');
?? ?? var list = document.getElementById('list');
?? ?? var buttons = document.getElementById('buttons').getElementsByTagName('span');
?? ?? var prev = document.getElementById('prev');
?? ?? var next = document.getElementById('next');

?? ?? next.onclick = function(){
?? ??? ?list.style.left = parseInt(list.style.left) - 520 + 'px';
?? ?? }
?? ?? prev.onclick = function(){
?? ??? ?list.style.left = parseInt(list.style.left) + 520 + 'px';
?? ?? }
?? ?}
? </script>
</head>
<body>
? <div id="container">
??? <div id="list" style="left:-520px;">
?? ?? <img src="../statics/images/5.jpg" alt="5">
?? ?? <img src="../statics/images/1.jpg" alt="1">
?? ?? <img src="../statics/images/2.jpg" alt="3">
?? ?? <img src="../statics/images/3.jpg" alt="3">
?? ?? <img src="../statics/images/4.jpg" alt="4">
?? ?? <img src="../statics/images/5.jpg" alt="5">
?? ?? <img src="../statics/images/1.jpg" alt="1">
?? ?</div>
?? ?<div id="buttons">
?? ?? <span index="1" class="on"></span>
?? ?? <span index="2"></span>
?? ?? <span index="3"></span>
?? ?? <span index="4"></span>
?? ?? <span index="5"></span>
?? ?</div>
?? ?<a href="javascript:;" id="prev" class="arrow"><</a>
?? ?<a href="javascript:;" id="next" class="arrow">></a>
? </div>
</body>
</html>