js+html+css实现手动轮播和自动轮播

Z时代
2024-01-10
分类：IT

本文实例为大家分享了js+html+css实现手动轮播和自动轮播的具体代码，供大家参考，具体内容如下

原理：设置图片层的总长=单张图片长度*张数；在轮播层中利用overflow只留出一张图片的显示；通过图片层的left来显示轮播的每一张图，第一张为0，为了后面的图片显示，left的值左移为负数。

原理图

代码：


<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>轮播图</title>
<!-- <script type="text/javascript" src="demo.js"></script> -->
</head>
<style type="text/css">
 *{
 margin: 0;
 padding: 0;
 }
 ul{
 list-style: none;
 }
 a{
    text-decoration: none;
  }
 #container{
 position: relative;
 width: 500px;
 height: 260px;
 margin: 20px auto;
 overflow: hidden; /*溢出隐藏：只显示一张图片*/
 }
 #container .parent{
 position: absolute;
 width: 2500px; /*整个图片层长度：500*5=2500*/
 height: 260px;
 }
 #container .parent li{
 float: left;
 width: 500px;
 height: 100%;
 }
 #container .parent li img{
 width: 100%;
 height: 100%;
 }
 #container .btnLeft,
 #container .btnRight{
 width: 30px;
   height: 30px;
   background-color: #9E9E9E;
   border-radius: 20%;
   opacity: 80%;
   position: absolute; /*包含块为图片显示层container*/
   top: 0;
   bottom: 0;
   margin: auto;
   font-size: 20px;
   color: #f40;
   text-align: center;
   line-height: 30px;
 }
 #container .btnLeft{
   left: 10px;
 }
 #container .btnRight{
 right: 10px;
 }
 #container .btnLeft:hover,
 #container .btnRight:hover{
 opacity: 90%;
 cursor: pointer;
 }
 /*蒙层*/
 #container .modal{
 width: 100%;
 height: 40px;
 background: rgba(0,0,0,.3);
 position: absolute;
 left: 0;
 bottom: 0;
 line-height: 40px;
 padding: 0 40px;
 box-sizing: border-box;
 }
 #container .modal .title{
 float: left;
 color: #fff;
 font-size: 12px;
 }
 #container .modal .dots{
 float: right;
 position: absolute;
 bottom: 10px;
 left: 340px;
 }
 #container .modal .dots li{
 width: 15px;
 height: 15px;
 border-radius: 50%;
 float: left;
 /*可以使用行块盒*/
 /*display: inline-block;*/
 margin: 0 5px;
 cursor: pointer;
 }
 .clearfix::after{
 content: "";
 display: block;
 clear: both;
 }
 .on{
 background-color: red;
 }
 .off{
 background-color: gray;
 }
</style>
<body>
<div id="container">
 <ul class="parent" style="left: 0;">
 <li><img src="1.jpg"></li>
 <li><img src="2.jpg"></li>
 <li><img src="3.jpg"></li>
 <li><img src="4.jpg"></li>
 <li><img src="5.jpg"></li>
 </ul>
 <div class="btnLeft">&lt;</div>
 <div class="btnRight">&gt;</div>
 <div class="modal">
 <div class="title">
  <h2>轮播图</h2>
 </div>
 <div class="dots">
  <ul class="clearfix">
  <li class="on"></li>
  <li class="off"></li>
  <li class="off"></li>
  <li class="off"></li>
  <li class="off"></li>
  </ul>
 </div>
 </div>
</div>
<script type="text/javascript">
var imgShow = document.getElementsByClassName('parent')[0],
 dotList = document.querySelectorAll('.dots >.clearfix > li');
var btnLeft = document.getElementsByClassName('btnLeft')[0],
  btnRight = document.getElementsByClassName('btnRight')[0];
var dotLen = dotList.length,
 index = 0; //轮播层的图片索引，0表示第一张
//圆点显示
function showRadius() {
 for(var i = 0; i < dotLen; i++) {
 if(dotList[i].className === "on"){
  dotList[i].className = "off";
 }
 }
 dotList[index].className = "on";
}
//向左移动
btnLeft.onclick = function() {
 index--;
  if(index < 0){ /*第1张向左时，变为第5张*/
    index = 4;
  }
  showRadius();
 var left;
 var imgLeft = imgShow.style.left;
 if(imgLeft === "0px") { /*当是第1张时，每张图片左移，移4张图，位置为-(4*500)*/
 left = -2000;
 }
 else{
 left = parseInt(imgLeft) + 500; /*由于left为负数，每左移一张加500*/
 }
 imgShow.style.left = left + "px";
}
//向右移动
btnRight.onclick = function() {
 index++;
  if(index > 4){ /*第5张向右时，变为第1张*/
    index = 0;
  }
  showRadius();
 var right;
 var imgLeft = imgShow.style.left;
 if(imgLeft === "-2000px") { /*当是第5张时，第1张的位置为0*/
 right = 0;
 }
 else{
 right = parseInt(imgLeft) - 500; /*由于left为负数，每右移一张减500*/
 }
 imgShow.style.left = right + "px";
}
// 自动轮播
/*var timer;
function autoPlay() {
 timer = setInterval(function() {
 var right;
 var imgLeft = imgShow.style.left;
 if(imgLeft === "-2000px") {
  right = 0;
 }
 else{
  right = parseInt(imgLeft) - 500;
 }
 imgShow.style.left = right + "px";
 } ,1000)
}
autoPlay();*/
for(var i = 0; i < dotLen; i++) {
  /*利用闭包传递索引*/
  (function(i) {
    dotList[i].onclick = function() {
     var dis = index - i; //当前位置和点击的距离
     imgShow.style.left = (parseInt(imgShow.style.left) + dis * 500) + "px";
     index = i; //显示当前位置的圆点
     showRadius();
   }
  })(i);
}
</script>
</body>
</html>