求这种 js 效果 应该这么写 给点代码提示

当我点击下一页时候 切换成div2  其他的隐藏  如此循环显示隐藏   用键盘控制也是一样的效果 
              
------解决方案--------------------<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
div{
	width:400px;
	height:400px;
}
.c1{
	background-color:#F00;
}
.c2{
	background-color:#0F0;
}
.c3{
	background-color:#00F;
}
</style>
<script type="text/javascript">
var test={
	divs:"",
	num:0,
	spans:"",
	init:function(){
		this.divs=document.getElementsByTagName("div");
		this.spans=document.getElementsByTagName("span");
		for(var i=1,len=this.divs.length;i<len;i++){
			this.divs[i].style.display="none";
		}
		var me=this;
		this.spans[0].onclick=function(){
			me.change(-1);
		}
		this.spans[1].onclick=function(){
			me.change(1);
		}
		document.onkeydown=function(e){
			var a=e
------解决方案--------------------window.event;
			if(a.keyCode==37){
				me.change(-1);
			}else if(a.keyCode==39){
				me.change(1);
			}
		}
	},
	change:function(x){
		var len=this.divs.length;
		this.num+=x;
		this.num=this.num==len?0:this.num;
		this.num=this.num<0?len-1:this.num;
		for(var i=0;i<len;i++){
			if(i!=this.num){
				this.divs[i].style.display="none";
			}else{
				this.divs[i].style.display="block";
			}
		}
	}
}
window.onload=function(){
	test.init.call(test);
}
</script>
</head>
<body>
<div class="c1">1</div>
<div class="c2">2</div>
<div class="c3">3</div>
<span>上一页</span>
<span>下一页</span>
</body>
</html>
类似这样试试
------解决方案--------------------