
<body>
<img src="banner_1.jpg" id="banner_1" style="position:absolute;z-index:1;">
<img src="right.png" id="right" style="position:absolute;z-index:2;top:150px;left:1400px;" >
<img src="left.png" id="left" style="position:absolute;z-index:2;top:150px;left:20px;" >
<script type="text/javascript">
var flag=0;
var flag2=0;
var img=document.getElementById("right");
var img1=document.getElementById("banner_1")
var img2=document.getElementById("left");
img.onclick=function fun(){
if(flag == 0){
img1.src="banner_2.jpg";
flag=1;
flag2=2;
}
else if(flag==1){
img1.src="banner_3.jpg";
flag=2;
flag2=1;
}
else if(flag==2){
img1.src="banner_1.jpg";
flag=0;
flag2=0;
}
}
img2.onclick=function fun2(){
if(flag2 == 0){
img1.src="banner_3.jpg";
flag2=1;
flag=2;
}