请问怎么做图片轮播的左右切换按钮 - 编程论坛

程序代码：

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
*{ margin:0px; padding:0px;}
.main{ width:600px; height:400px; margin:0px auto; border:1px solid #0F6;}
.main_img{ width:600px; height:300px; float:left;}
.main_banner{ width:149px; height:100px; float:left; margin-right:1px;}
.butto{ color:#F00; width:50px; height:100px;}
</style>
</head>

<body>
<div class="main">
<img src="images/pp.png" class="main_img" onmouseover="pp()" onmouseout="xx()">
<img src="images/qwe.png" class="main_banner" onClick="hh(this)">
<img src="images/trt.png" class="main_banner" onClick="hh(this)">
<img src="images/ww.png" class="main_banner" onClick="hh(this)">
<img src="images/ww.png" class="main_banner" onClick="hh(this)">

</div>

</body>
<script>

var x=document.getElementsByTagName('img');
var y=2,z=0;
var st=setInterval('changE()',1000);
function changE(){
    y--;
    if(y==0){
        x[0].src=x[z].src;
        z++;
        y=2;
        }
    if(z>4)
    z=0;
    }

function xx(){
     st=setInterval('changE()',1000);
    }
function pp(){
    clearTimeout(st);}
function hh(obj){
    x[0].src=obj.src;
    }

</script>
</html>