javascript实现图片轮播代码

<div id="head"> <button id="prev" onmousedown="p()" onmouseout="cal()"><</button><img height="500px" width="500px" src="image/dell.jpg" style="margin: 0px; padding: 0px; outline: none; line-height: 25.2px; font-size: 14px; width: 660px; overflow: hidden; clear: both; font-family: tahoma, arial, "Microsoft YaHei";">	
<style type="text/css">*{ margin: 0; padding: 0;}#head{ width:800px; height:500px; border-radius: 5px; border: 2px solid pink; margin: 200px auto; text-align: center; }#prev{ width: 30px; height: 30px; border: 0px; border-radius: 5px; background-color:white; color: black; position: relative; margin-top: 250px; float: left; }#next{ width: 30px; height: 30px; border: 0px; border-radius: 5px; background-color:white; color: black; position: relative; margin-top: 250px; float: right; }</style>

<script> var prev=document.getElementById("prev"); var next=document.getElementById("next"); var img=document.getElementsByTagName("img")[0]; var imgArr=["image/dell.jpg/dell.jpg","image/dell.jpg/sony.jpg","image/dell.jpg/费列罗.jpg","image/dell.jpg/Nike.jpg"]; var index=0;  //点击左箭头，切换上一张 function p(){ if(index==0) {  index=imgArr.length; } index--; img.src=imgArr[index]; } //点击右箭头，切换下一张 function n(){ if(index==imgArr.length) {  index=0; } img.src=imgArr[index]; index++; } //设置自动播放 time=setInterval("p()",2000);  //鼠标移入箭头内，停止自动播放 function cal(){ clearInterval(time); }</script>