轮播图的实现，点击按钮切换轮播图等功能

本文链接：https://blog.youkuaiyun.com/a815886696/article/details/108714787

菜单区域实现
划过主菜单显示子菜单

轮播区域实现
1、点击图片中左右箭头，分别跳转上一张与下一张
（1）点击上一张图其实就是让一个变量进行递减，点击下一张图就是让变量递增；（控制索引最大最小值）
2、点击右下角小圆也可以进行图片的跳转
（1）通过索引让变量进行随意的修改
3、每间隔3s进行轮播图的自动切换，鼠标放在图片上清除自动切换
（1）定时器
4、鼠标放在主菜单上显示子菜单，离开子菜单消失。
放在子菜单上显示子菜单，离开消失。

源代码：
html

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>轮播图</title>
	<link rel="stylesheet" type="text/css" href="css/style.css"/>
	<script type="text/javascript" src="js/script.js"></script>
</head>
<body>
	<div class="main" id="main">
		<!-- 主菜单背景 -->
		<div class="menu-box"></div>
		<!-- 主菜单 -->
		<div class="menu-content" id="menu-content">
			<div class="menu-item">
				<a href="">
					<span>手机、配件</span>
					<i class="icon">&#xe665;</i>
				</a>
			</div>
			<div class="menu-item">
				<a href="">
					<span>电脑</span>
					<i class="icon">&#xe665;</i>
				</a>
			</div>
			<div class="menu-item">
				<a href="">
					<span>家用电器</span>
					<i class="icon">&#xe665;</i>
				</a>
			</div>
			<div class="menu-item">
				<a href="">
					<span>家具</span>
					<i class="icon">&#xe665;</i>
				</a>
			</div>
		</div>
		<!-- 子菜单 -->
		<div class="sub-menu hide" id="sub-menu">
			<!-- 子菜单背景 -->
			<div class="inner-box">
				<!-- 子菜单内容 -->
				<div class="sub-inner-box">
					<div class="title">手机、配件</div>
					<div class="sub-row">
						<span class="bold mr10">手机通讯：</span>
						<a href="">手机</a>
						<span class="ml10 mr10">/</span>
						<a href="">手机维修</a>
						<span class="ml10 mr10">/</span>
						<a href="">以旧换新</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">手机配件：</span>
						<a href="">手机壳</a>
						<span class="ml10 mr10">/</span>
						<a href="">手机储蓄卡</a>
						<span class="ml10 mr10">/</span>
						<a href="">数据线</a>
						<span class="ml10 mr10">/</span>
						<a href="">充电器</a>
						<span class="ml10 mr10">/</span>
						<a href="">电池</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">运营商：</span>
						<a href="">中国联通</a>
						<span class="ml10 mr10">/</span>
						<a href="">中国移动</a>
						<span class="ml10 mr10">/</span>
						<a href="">中国电信</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">智能设备：</span>
						<a href="">智能手环</a>
						<span class="ml10 mr10">/</span>
						<a href="">智能家居</a>
						<span class="ml10 mr10">/</span>
						<a href="">智能手表</a>
						<span class="ml10 mr10">/</span>
						<a href="">其他配件</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">娱乐：</span>
						<a href="">耳机</a>
						<span class="ml10 mr10">/</span>
						<a href="">音响</a>
						<span class="ml10 mr10">/</span>
						<a href="">收音机</a>
						<span class="ml10 mr10">/</span>
						<a href="">麦克风</a>
					</div>
				</div>
			</div>
			<div class="inner-box">
				<div class="sub-inner-box">
					<div class="title">电脑</div>
					<div class="sub-row">
						<span class="bold mr10">电脑：</span>
						<a href="">笔记本</a>
						<span class="ml10 mr10">/</span>
						<a href="">平板</a>
						<span class="ml10 mr10">/</span>
						<a href="">一体机</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">电脑配件：</span>
						<a href="">显示器</a>
						<span class="ml10 mr10">/</span>
						<a href="">CPU</a>
						<span class="ml10 mr10">/</span>
						<a href="">主板</a>
						<span class="ml10 mr10">/</span>
						<a href="">硬盘</a>
						<span class="ml10 mr10">/</span>
						<a href="">电源</a>
						<span class="ml10 mr10">/</span>
						<a href="">显卡</a>
						<span class="ml10 mr10">/</span>
						<a href="">其他配件</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">游戏设备：</span>
						<a href="">游戏机</a>
						<span class="ml10 mr10">/</span>
						<a href="">耳机</a>
						<span class="ml10 mr10">/</span>
						<a href="">游戏软件</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">网络产品：</span>
						<a href="">路由器</a>
						<span class="ml10 mr10">/</span>
						<a href="">网络机顶盒</a>
						<span class="ml10 mr10">/</span>
						<a href="">交换机</a>
						<span class="ml10 mr10">/</span>
						<a href="">存储卡</a>
						<span class="ml10 mr10">/</span>
						<a href="">网卡</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">外部产品：</span>
						<a href="">鼠标</a>
						<span class="ml10 mr10">/</span>
						<a href="">键盘</a>
						<span class="ml10 mr10">/</span>
						<a href="">U盘</a>
						<span class="ml10 mr10">/</span>
						<a href="">移动硬盘</a>
						<span class="ml10 mr10">/</span>
						<a href="">鼠标垫</a>
						<span class="ml10 mr10">/</span>
						<a href="">电脑清洁</a>
					</div>
				</div>
			</div>
			<div class="inner-box">
				<div class="sub-inner-box">
					<div class="title">家用电器</div>
					<div class="sub-row">
						<span class="bold mr10">电视：</span>
						<a href="">国产品牌</a>
						<span class="ml10 mr10">/</span>
						<a href="">韩国品牌</a>
						<span class="ml10 mr10">/</span>
						<a href="">欧美品牌</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">空调：</span>
						<a href="">显示器</a>
						<span class="ml10 mr10">/</span>
						<a href="">柜式</a>
						<span class="ml10 mr10">/</span>
						<a href="">中央</a>
						<span class="ml10 mr10">/</span>
						<a href="">壁挂式</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">冰箱：</span>
						<a href="">多门</a>
						<span class="ml10 mr10">/</span>
						<a href="">对开门</a>
						<span class="ml10 mr10">/</span>
						<a href="">三门</a>
						<span class="ml10 mr10">/</span>
						<a href="">双门</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">洗衣机：</span>
						<a href="">滚筒式洗衣机</a>
						<span class="ml10 mr10">/</span>
						<a href="">迷你洗衣机</a>
						<span class="ml10 mr10">/</span>
						<a href="">洗烘一体机</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">厨房电器：</span>
						<a href="">抽烟机</a>
						<span class="ml10 mr10">/</span>
						<a href="">洗碗机</a>
						<span class="ml10 mr10">/</span>
						<a href="">燃气灶</a>
					</div>
				</div>
			</div>
			<div class="inner-box">
				<div class="sub-inner-box">
					<div class="title">家具</div>
					<div class="sub-row">
						<span class="bold mr10">家纺：</span>
						<a href="">被子</a>
						<span class="ml10 mr10">/</span>
						<a href="">枕头</a>
						<span class="ml10 mr10">/</span>
						<a href="">四件套</a>
						<span class="ml10 mr10">/</span>
						<a href="">床垫</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">灯具：</span>
						<a href="">台灯</a>
						<span class="ml10 mr10">/</span>
						<a href="">顶灯</a>
						<span class="ml10 mr10">/</span>
						<a href="">节能灯</a>
						<span class="ml10 mr10">/</span>
						<a href="">应急灯</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">厨具：</span>
						<a href="">烹饪锅具</a>
						<span class="ml10 mr10">/</span>
						<a href="">餐具</a>
						<span class="ml10 mr10">/</span>
						<a href="">菜板刀具</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">家装：</span>
						<a href="">地毯</a>
						<span class="ml10 mr10">/</span>
						<a href="">沙发垫套</a>
						<span class="ml10 mr10">/</span>
						<a href="">装饰字画</a>
						<span class="ml10 mr10">/</span>
						<a href="">照片墙</a>
						<span class="ml10 mr10">/</span>
						<a href="">窗帘</a>
					</div>
					<div class="sub-row">
						<span class="bold mr10">生活日用：</span>
						<a href="">收纳用品</a>
						<span class="ml10 mr10">/</span>
						<a href="">浴室用品</a>
						<span class="ml10 mr10">/</span>
						<a href="">雨伞雨衣</a>
					</div>
				</div>
			</div>
		</div>
		<!-- 焦点图 -->
		<div class="banner" id="banner">
			<!-- 鼠标悬停停止自动轮播的区域 -->
			<section class="cease" id="cease"></section>
			<a href="">
				<div class="banner-slide slide1"></div>
			</a>
			<a href="">
				<div class="banner-slide slide2"></div>
			</a>
			<a href="">
				<div class="banner-slide slide3"></div>
			</a>
		</div>
		<!-- 按钮 -->
		<a href="javascript:void(0)" class="button prev" id="prev"></a>
		<a href="javascript:void(0)" class="button next" id="next"></a>
		<div class="dots" id="dots">
			<span class="active"></span>
			<span></span>
			<span></span>
		</div>
	</div>
</body>
</html>

css

*{
	margin: 0;
	padding: 0;
}
/*通配符选择器，外边距，内边距为0*/
body{
	font-family: "微软雅黑";
	color: #14191e;
}
/*字体，字体颜色*/
@font-face{
	font-family: 'iconfont';/*自定义名称，要有意义，不准数字*/
	src: url('../font/iconfont.eot');/*兼容ie9以上版本*/
	src: url('../font/iconfont.eot?#iefix') format('embedded-opentype'),/*兼容ie6-8版本*/
	url('../font/iconfont.ttf') format('truetype'),/*主要针对手机端浏览器  safari  android  ios*/
	url('../font/iconfont.woff') format('woff'),/*兼容所有浏览器 */
	url('../font/iconfont.svg#iconfont') format('svg');/*针对ios端开发   legacy ios*/
/*	font-weight: bold;<字体加粗>
	font-style: normal;默认的正常显示*/
}
/*获取下载的字体*/
a{
	text-decoration: none;
}
/*没有下划线*/
a:link,a:visited{
	color: #5e5e5e;
}
/*联合选择器，未访问连接时与已经访问链接时的字体颜色*/
.main{
	width: 1200px;
	height: 460px;
	margin: 30px auto;
	overflow: hidden;
	position: relative;
}
/*最大框架：宽；高；外边距，上下30px，左右居中；溢出的部分隐藏；相对定位*/
.banner{
	width: 1200px;
	height: 460px;
	overflow: hidden;
	cursor: pointer;
}
/*焦点图：宽；高；溢出的部分隐藏；小手标志*/
.banner-slide{
	width: 1200px;
	height: 460px;
	float: right;
	background-repeat: no-repeat;
	display: none;
}
/*三个图片：宽；高；右浮动，背景不重复;全部隐藏*/

.slide1{
	background-image: url(../img/bg1.jpg);
	display: block;
}
/*第一个图片;块级元素显示*/
.slide2{
	background-image: url(../img/bg2.jpg);
}
/*第二个图片*/
.slide3{
	background-image: url(../img/bg3.jpg);
}
/*第三个图片*/
.button{
	position: absolute;
	width: 40px;
	height: 80px;
	right: 0;
	background: url(../img/arrow.png) center center no-repeat;
	top: 50%;
	margin-top: -40px;
}
/*左右两个按钮；宽；高；相对main绝对定位，距右0，距上50%；背景图片，水平垂直居中，不重复；外上边距-40px；*/
.button:hover{
	background-color: #333;
	opacity: 0.8;
	filter: alpha(opacity=80);
}
/*鼠标悬浮在上面时状态：背景颜色，透明度。照顾IE浏览器*/
.prev{
	left: 244px;
	-webkit-transform: rotate(180deg);
	   -moz-transform: rotate(180deg);
	    -ms-transform: rotate(180deg);
	     -o-transform: rotate(180deg);
		    transform: rotate(180deg);
}
/*左按钮相对上面：靠左244px，定位左的优先级高于右；旋转180度*/
.dots{
	position: absolute;
	right: 24px;
	bottom: 24px;
	line-height: 12px;
}
/*下面三个选择圆：相对main绝对定位，距右，距下，行间距12px；*/
.dots span{
	display: inline-block;
	width: 12px;
	height: 12px;
	border-radius: 50%;
	background-color: rgba(7,17,27,.4);
	margin-left: 8px;
	box-shadow: 0 0 0 2px rgba(255,255,255,.8) inset;
	cursor: pointer;
}
/*子孙后代选择器：转换为块级元素并列一排；宽；高；削圆；背景颜色；外左边距，让他们之间有距离；盒子阴影，水平偏移量，垂直偏移量，模糊度，扩展多少，颜色模糊度，内阴影;小手标志*/
.dots .active{
	background-color: #fff;
	box-shadow: 0 0 0 2px rgba(255,255,255,.4) inset;
}
/*背景颜色，同上*/
.menu-box{
	position: absolute;
	left: 0;
	top: 0;
	width: 244px;
	height: 460px;
	background: rgba(7,17,27,.3);
	z-index: 1;
}
/*主菜单背景，相对main绝对定位，左上偏移；宽；高；背景颜色模糊度；层叠模式数字大的在上面显示*/
.menu-content{
	position: absolute;
	left: 0;
	top: 0;
	width: 244px;
	height: 460px;
	z-index: 2;
}
/*主菜单（因为菜单不需要模糊度所以单独拿出来设置css样式）*/
.menu-item{
	height: 64px;
	line-height: 66px;
	cursor: pointer;
	padding: 0 24px;
}
/*主菜单的每个标题，宽；行间距；因为是链接，浮在上面显示小手标志；内边距，上下0，左右24px；下划线两边留空*/
.menu-item a{
	display: block;
	color: #fff;
	font-size: 16px;
	border-bottom: 1px solid rgba(255,255,255,.2);
	height: 63px;
	position: relative;
}
/*转换为块级元素；字体颜色；字体大小；下边框，粗细，实线，颜色透明度；高；相对定位*/
.menu-item:last-child a{
	border-bottom:none;
}
/*menu-item的最后一个元素a；没有下边框*/
.menu-item i{
	position: absolute;
	right: 12px;
	top: 2px;
	color: rgba(255,255,255,.5);
	font-style: normal;
	font-weight: normal;
	font-family: "iconfont";
	font-size: 24px;
}
/*子孙后代选择器：相对a绝对定位；右下偏移；字体颜色模糊度；没有斜体；没有加粗；字体；字体大小*/
.sub-menu{
	width: 730px;
	height: 458px;
	position: absolute;
	left: 244px;
	top: 0;
	background: #fff;
	z-index: 50;
	border: 1px solid #d9dde1;
	box-shadow: 0 4px 8px 0px rgba(0,0,0,.1);
}
/*子菜单：宽；高；相对main绝对定位，左上偏移；背景颜色；层叠模式数字大的在上面显示；边框；盒子阴影*/
.inner-box{
	width: 100%;
	height: 100%;
	background: url(../img/fe.png);
	display: none;
}
/*子菜单背景：宽；高；背景图片;全部隐藏*/
.sub-inner-box{
	width: 652px;
	margin-left: 40px;
	overflow: hidden;
}
/*子菜单内容；宽；外左边距；溢出的内容隐藏*/
.title{
	font-size: 16px;
	color: #f01414;
	line-height: 16px;
	font-weight: bold;
	margin: 28px 0 30px 0;
}
/*子菜单内容的标题：字体大小；颜色；行高；粗体；外边距*/
.sub-row{
	margin-bottom: 25px;
}
/*子菜单内容：外下边距让他们之间有距离*/
.bold{
	font-weight: bold;
}
/*子标题：字体加粗*/
.ml10{
	margin-left: 10px;
}
/*内容和斜杠之间的左边距离*/
.mr10{
	margin-right: 10px;
}
/*内容、子标题和斜杠之间的右边距离*/
.hide{
	display: none;
}
/*隐藏子菜单*/

// 声明全局变量
window.onload=function(){
 	var index = 0,//当前显示图片的索引，默认值为0
 		timer = null, //定时器
 		cease = byId("cease"),//鼠标悬停停止自动轮播的区域
 		prev = byId("prev"),//上一张
 		next = byId("next"),//下一张
 		banner = byId("banner"),//焦点图的爷爷
 		pics = banner.getElementsByTagName('div'),//焦点图
 		dots = byId("dots").getElementsByTagName('span'),//圆点
 		menuContent = byId("menu-content"),//主菜单
 		menuItems = menuContent.getElementsByClassName("menu-item"),//主菜单的标题
 		subMenu = byId("sub-menu"),//子菜单
 		innerBox = subMenu.getElementsByClassName("inner-box"),//子菜单的标题
 		mlen = menuItems.length,
 		size = pics.length,
 		llen = innerBox.length;
 		// console.log(size);






console.log(lis_1[0]);
lis_1[0].onclick = function(){
	department.className = 'hide'
	hospital.className = 'hospital'
	lis_1[0].className = 'li_1'
}
lis_1[1].onclick = function(){
	department.className = ''
	hospital.className = 'hospital hide'
	lis_1[1].className = 'li_1'
}



//封装getElementById（）三元运算符
function byId(id){
	return typeof(id) === "string" ? document.getElementById(id):id;
}

/*封装通用事件绑定方法；
			element绑定事件的DOM元素
			事件名
			事件处理程序
*/
function addHandler(element,type,handler){
	//针对非IE浏览器
	if (element,addEventListener) {
		element.addEventListener(type,handler,true);
	} 	//IE浏览器支持DOM2级
	else if (element,attachEvent) {
		element.attachEvent('on' + type,handler);
	}	//IE浏览器不支持DOM2级，使用DOM0级
	else{
		element['on' + type] = handler;
		//变量不可以.type，事件可以.；
	}
}

//封装函数，切换图片
function changImg(){
	//遍历所有图片，将图片隐藏，将圆点上的类清除
	for(var i=0;i<size;i++){
	pics[i].style.display = 'none';
	dots[i].className = "";
	}
	//显示当前图片
	pics[index].style.display = 'block';
	//当前圆点高亮显示
	dots[index].className = "active";
}

// 点击下一张按钮显示下一张图片
addHandler(next,"click",function(){
	index++;
	if (index>=size) index = 0;
	changImg();
});

// 点击上一张按钮显示上一张图片
addHandler(prev,"click",function(){
	index--;
	if (index<0) index = size-1;
	changImg();
});

//点击圆点索引切换图片
for(var j=0;j<size;j++){
	dots[j].setAttribute('tid',j);
	addHandler(dots[j],'click',function(){
		//自定义属性不可以直接点，需用getAttribute
		index = this.getAttribute('tid');
		changImg();
	})
}

//定时器,开启自动轮播
function startAutoPlay(){
	timer = setInterval(function(){
		index++;
		if (index>=size) index = 0;
		changImg();
	},3000)
}

//清除定时器，停止自动轮播
function ceaseAutoPlay(){
	if(timer){
		clearInterval(timer);
	}
}

//封装函数，取消所有主菜单背景
function bgNone(){
	for(var n=0;n<mlen;n++){
		menuItems[n].style.background = 'none';
	}
}

//封装函数，子菜单和主菜单背景显示
function menuItemsBg(){
	//显示子菜单所在的背景
	subMenu.className = "sub-menu";
	//获取当前主菜单的索引
	index = this.getAttribute('data-index');
	//遍历所有的子菜单innerbox，将它们隐藏
	for(var l=0;l<llen;l++){
		//隐藏所有的子菜单
		innerBox[l].style.display = "none";
		//所有主菜单取消背景
		menuItems[l].style.background = 'none';
	}
	//找到当前子菜单，让其显示出来
	innerBox[index].style.display = "block";
	//当前主菜单显示背景
	menuItems[index].style.background = 'rgba(0,0,0,.1)';
}

//鼠标滑过主菜单和子菜单
for(var k=0;k<mlen;k++){
	//给所有主菜单定义属性，表明它的索引
	menuItems[k].setAttribute('data-index',k);
	//给所有子菜单定义属性，表明它的索引
	innerBox[k].setAttribute('data-index',k);
	addHandler(menuItems[k],"mouseover",menuItemsBg)
	addHandler(innerBox[k],"mouseover",menuItemsBg)
}

//鼠标滑入子菜单，显示子菜单
addHandler(subMenu,"mouseover",function(){
	subMenu.className = "sub-menu";
})

//鼠标离开主菜单，隐藏子菜单
addHandler(menuContent,"mouseout",function(){
	subMenu.className = "sub-menu hide";
	bgNone();	
})

//鼠标离开子菜单，隐藏子菜单
addHandler(subMenu,"mouseout",function(){
	subMenu.className = "sub-menu hide";
	bgNone();
})

//鼠标滑入cease，停止轮播
addHandler(cease,"mouseover",ceaseAutoPlay);
//鼠标离开cease，继续轮播
addHandler(cease,"mouseout",startAutoPlay);

//自动开启轮播
startAutoPlay();

}