轮播图换背景

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>轮播图换背景</title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			.bg{
				width: 1000px;
				height: 500px;
				border: 1px solid black;
				margin: 0px auto;
				position: relative;
				overflow: hidden;
			}
			.img{
				width: 4000px;
				height: 500px;
				transition: all 1s;
			}
			.img div{
				width: 1000px;
				height: 500px;
				float: left;
			}
			.button{
				position: absolute;
				width: 50px;
				height: 100px;
				background-color: darkgray;
				top: 0px;
				bottom: 0px;
				margin: auto;
			}
			.right{
				right: 0px;
			}
			.span{
				width: 100%;
				height: 50px;
				position: absolute;
				bottom: 0px;
				text-align: center;
			}
			.span span{
				width: 20px;
				height: 20px;
				background-color:white;
				display: inline-block;
				border-radius: 20px;
				margin: 10px 10px;
			}
			button{
				display: block;
				margin: 10px auto;
			}
			.span .cur{/*.span必须加,关于类名的约分优先级高低，点击时触发的样式*/
				background-color: red;
			}
		</style>
	</head>
	<body>
		<div class="bg">
			<div class="img">
				<div style="background-color: lightblue;"></div>
			    <div style="background-color: lightcoral;"></div>
			    <div style="background-color: lightgray;"></div>
			    <div style="background-color: lightgreen;"></div>
			</div>
			<div class="button left"></div>
			<div class="button right"></div>
			<div class="span">
				<span class="cur"></span>
				<span></span>
				<span></span>
				<span></span>
			</div>
		</div>
		<button>点击收起</button>
	</body>
	<script type="text/javascript">
		var left=document.querySelector('.left');
		var right=document.querySelector('.right');
		var box=document.querySelector('.img');
		var img=document.querySelectorAll('.img div');
		var span=document.querySelectorAll('.span span');
		var btn=document.querySelector('button');
		var bg=document.querySelector('.bg');
		var num=0;//用来记录轮播图上的左右按钮被点击的次数
		var ga=0//用来记录展开收起按钮被点击的次数
		right.onclick=function()//右按钮点击事件
		{
			num++;
			if(num>=4)
			{
				num=0;
			}
			for(var y=0;y<span.length;y++)
				{
					span[y].className='';
				}
				span[num].className='cur';
			    box.style.marginLeft=-1000*num+'px';
		}
		left.onclick=function()//左按钮点击事件
		{
			num--;
			if(num<=-1)
			{
				num=3;
			}
			for(var y=0;y<span.length;y++)
				{
					span[y].className='';
				}
				span[num].className='cur';
			    box.style.marginLeft=-1000*num+'px';
		}
		for(var x=0;x<img.length;x++)//换背景点击事件
		{
			img[x].onclick=function()
			{
				document.body.style.backgroundColor=this.style.backgroundColor;//如果是换背景图片，需要将图片设置为background(背景图片)样式
			}
		}
		btn.onclick=function()//盒子点击展开收起事件
		{
			if(ga%2==0)//判断盒子展开收起按钮被点击的次数是哪一次
			{
				bg.style.height='0px';//盒子收起状态
				btn.innerHTML='点击展开';
			}
			else
			{
				bg.style.height='500px';//盒子展开状态
				btn.innerHTML='点击收起';
			}
			ga++;
		}
		for(var x=0;x<span.length;x++)//小圆点点击
		{
			span[x].a=x;//获取每一个小圆点的下标
			span[x].onclick=function()
			{
				for(var y=0;y<span.length;y++)
				{
					span[y].className='';
				}
				this.className='cur';
				box.style.marginLeft=-1000*this.a+'px';//this.a就表示小圆点的下标
				num=this.a;//将小圆点的点击与总点击次数进行绑定
			}
		}
	</script>
</html>