轮播效果：
1、鼠标没有移入到banner,自动轮播
2、鼠标移入：取消自动轮播、移除开始自动轮播
3、点击指示点开始轮播到对应位置
4、点击前一个后一个按钮，轮播到上一个下一个图片
注意
最后一个图片无缝滚动，就是先克隆第一个图片，把它放到最后面。
当轮播到最后视觉最后一个图片下一个图片理想应该是播放第一个，但是这样直接到第一个会很生硬，所以在最后克隆了第一个图片，这样就会平滑的从视觉效果过度到第一个，再次播放下一个图的时候则使用xx.style.left = 0属性快速切为第一个(无动画效果)
轮播图.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><!-- 加载动画 --><script src="js/animate.js"></script><script src="js/banner.js"></script><style>*{margin: 0;}.box{width: 100vw;height: 100vh;padding-top:20px ;background-color: aliceblue;box-sizing: border-box ;}.box .ul-box{position: relative;margin: auto;width: 450px;height: 230px;overflow: hidden;/* background-color: #ff00aa; */}.ul-box #img-ul{position: absolute;width: 400%;/* 去除li样式 */list-style: none; /* 移除列表项前的符号 */padding-left: 0;margin: 0}.ul-box #img-ul li{background-color: rgb(202, 214, 225);/* opacity: 0.2; */width: 450px;height: 230px;float: left;}.ul-box #img-ul li img{width: 450px;height: 230px;}#dot-ul{position: absolute;bottom: 20px;left: 50%;transform: translateX(-50%);display: flex;background-color: rgb(232, 234, 234);opacity: 0.8;list-style: none; /* 移除列表项前的符号 */padding-left: 0;margin: 0;border-radius: 12px;}#dot-ul li{margin: 5px;height:10px;width: 10px;border: 1px solid #ffffff;border-radius: 50%;}.active{background-color: #ffffff;}.un-active{background-color: none;}/* 按钮 */#left-btn,#right-btn{position: absolute;top: 50%;transform: translateY(-50%);background-color: aliceblue;opacity: 0.5;border-radius: 5px;color: rgb(66, 66, 56);padding: 2px;}#left-btn{left: 0;}#right-btn{right: 0;}</style>
</head>
<body><div class="box"><div class="ul-box" id="ul-box"><ul id="img-ul"><li><img src="./imgs/1.png"></li><li> <img src="./imgs/2.png"></li><li> <img src="./imgs/3.png"></li></ul><ul id="dot-ul"><!-- <li class="active" > </li><li > </li><li > </li> --></ul><div id="left-btn"><</div><div id="right-btn">></div></div></div>
</body>
</html>
js文件夹下banner.js
window.addEventListener('load', () => {let timeGap = 20let allTime = 500let picWidth = 450let playTimer = null //自动播放let palyTime = 2000 + allTimelet currentIndex = 0 //当前播放// 包裹盒子let ulBox = document.getElementById('ul-box')// 获取ullet imgUlEl = document.getElementById('img-ul')// 获取img ul下的li个数let imgLiElList = imgUlEl.getElementsByTagName('li')// 指示点 ullet dotUlEl = document.getElementById('dot-ul')// 创建知识点 lifor (let i = 0; i < imgLiElList.length; i++) {// 创建元素let liEl = document.createElement('li')liEl.id = 'dotli-' + idotUlEl.appendChild(liEl)}// 克隆第一个图片if (imgLiElList.length) {let firstPicEl = imgLiElList[0]let cloneEl = firstPicEl.cloneNode(true)imgUlEl.appendChild(cloneEl)}// 获取指示点 li列表let dotLiEllist = dotUlEl.getElementsByTagName('li')//修改dot状态function changeDot() {for (let j = 0; j < dotLiEllist.length; j++) {let itemEl = dotLiEllist[j]itemEl.className = 'un-active'}if (currentIndex >= dotLiEllist.length) {// 如果是最后一个克隆的照片则默认指示点是第一个dotLiEllist[0].className = 'active'} else {dotLiEllist[currentIndex].className = 'active'}}// 第一个设置原点激活样式currentIndex = 0changeDot()// 指示点添加点击事件for (let i = 0; i < dotLiEllist.length; i++) {let elI = dotLiEllist[i]elI.addEventListener('click', () => {// 修改当前状态currentIndex = i//修改dot状态changeDot()// 计算需要移动的距离let distance = -picWidth * iconsole.log(distance)animate(imgUlEl, distance, timeGap, allTime)})}// 鼠标移动去除自动播放ulBox.addEventListener('mouseover', () => {console.log('mouseover')if (playTimer) {clearTimeout(playTimer)}})// 鼠标移除自动播放ulBox.addEventListener('mouseleave', () => {console.log('mouseleave')autoPlay()})// 自动播放图片function autoPlay() {playTimer = setTimeout(() => {if (currentIndex == dotLiEllist.length) {currentIndex = 0imgUlEl.style.left = 0}currentIndex++//判断是否是最后一个图片animate(imgUlEl, -picWidth * currentIndex, timeGap, allTime, () => {//修改dot状态changeDot()if (playTimer) {clearTimeout(playTimer)}autoPlay()})}, palyTime)}//调用自动播放autoPlay()// 按钮添加点击事件let btnLeft = document.getElementById('left-btn')let btnRight = document.getElementById('right-btn')btnLeft.style.cursor = 'grab'btnRight.style.cursor = 'grab'btnLeft.addEventListener('click', () => {if (currentIndex > 0) {currentIndex--animate(imgUlEl, -picWidth * currentIndex, timeGap, allTime)changeDot()}})btnRight.addEventListener('click', () => {// 滑动到最后一个克隆的照片if (currentIndex == dotLiEllist.length) {currentIndex = 1imgUlEl.style.left = 0} else {currentIndex++}animate(imgUlEl, -picWidth * currentIndex, timeGap, allTime)changeDot()})
})js文件夹下animate.js
// 给元素添加动画效果
// targetPosition 目标位置
// timeGap 每次移动时间间隔
// allTime 花费多久移动完
// callBack 回调函数
function animate(el, targetPosition, timeGap = 100, allTime = 1000, callBack) {let offsetX = el.offsetLeft//需要移动位置let distance = targetPosition - offsetX// 每隔一段时间移动一段距离let moveCount = allTime / timeGap // 总共移动多少次let moveDistance = distance / moveCount //每次移动多少距离let timer = setInterval(() => {// console.log(moveCount, moveDistance)offsetX = el.offsetLeft //相对父元素的距离el.style.left = offsetX + moveDistance + 'px'moveCount-- //移动次数减少distance = distance - moveDistance //总共需要移动的距离if (moveCount <= 0) {//防止没有计算完el.style.left = targetPosition + 'px'// 执行回调callBack ? callBack() : ''clearInterval(timer)}}, timeGap)
}图片资源
放到imgs文件夹下即可，对应命名为1.png、2.png、3.png即可
