原生JavaScript实现轮播图

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本文实例为大家分享了JavaScript实现轮播图的具体代码，供大家参考，具体内容如下

效果：

代码：

<!DOCTYPE html>
<html>

 <head>
 <meta charset="UTF-8">
 <title></title>
 <style>
 * {
 margin: 0;
 padding: 0;
 }
 
 ul,
 li {
 list-style: none;
 }
 
 .banner {
 width: 1200px;
 height: 535px;
 border: 1px solid red;
 margin: 0 auto;
 position: relative;
 }
 
 .slider li {
 position: absolute;
 left: 0;
 top: 0;
 }
 
 a {
 width: 40px;
 height: 50px;
 background-color: rgba(0, 0, 0, 0.1);
 font-size: 50px;
 text-align: center;
 line-height: 50px;
 position: absolute;
 text-decoration: none;
 color: gray;
 }
 
 .btnl {
 left: 0;
 top: 50%;
 margin-top: -15px;
 }
 
 .btnr {
 right: 0;
 top: 50%;
 margin-top: -25px;
 }
 
 .tabs {
 position: absolute;
 bottom: 20px;
 left: 50%;
 margin-left: -75px;
 }
 
 .tabs li {
 width: 15px;
 height: 15px;
 background-color: #ccc;
 border-radius: 50%;
 float: left;
 margin-right: 10px;
 }
 </style>
 </head>

 <body>
 <div class="banner">
 <ul class="slider">
 <li><img src="img/b1.jpg" alt="" /></li>
 <li><img src="img/b2.jpg" alt="" /></li>
 <li><img src="img/b3.jpg" alt="" /></li>
 <li><img src="img/b4.jpg" alt="" /></li>
 <li><img src="img/b5.jpg" alt="" /></li>
 <li><img src="img/b6.jpg" alt="" /></li>
 </ul>
 <a href="javascript:void(0);" class="btnl">
 <</a>
 <a href="javascript:void(0);" class="btnr">></a>
 <ul class="tabs">
 <li></li>
 <li></li>
 <li></li>
 <li></li>
 <li></li>
 <li></li>
 </ul>
 </div>
 <script type="text/javascript">
 var banner = document.getElementsByClassName("banner")[0];
 var slider = document.getElementsByClassName("slider")[0];
 var li = slider.getElementsByTagName("li");
 var btnl = document.getElementsByClassName("btnl")[0];
 var btnr = document.getElementsByClassName("btnr")[0];
 var tabs = document.getElementsByClassName("tabs")[0];
 var btns = tabs.getElementsByTagName("li");

 //初始化
 btns[0].style.backgroundColor = "red";

 for(var i = 0; i < li.length; i++) {
 if(i == 0) {
 continue;
 } else {
 li[i].style.opacity = 0;
 }
 }

 var timer = setInterval(mover, 1000);

 //声明一个变量，代表当前图片的下标
 var num = 0;

 function mover() {
 num++;
 if(num == li.length) {
 num = 0;
 }
 for(var i = 0; i < li.length; i++) {
 li[i].style.opacity = 0;
 btns[i].style.backgroundColor = "#ccc";
 }
 li[num].style.opacity = 1;
 btns[num].style.backgroundColor = "red";

 }

 function movel() {
 num--;
 if(num == -1) {
 num = li.length - 1;
 }
 for(var i = 0; i < li.length; i++) {
 li[i].style.opacity = 0;
 btns[i].style.backgroundColor = "#ccc";
 }
 li[num].style.opacity = 1;
 btns[num].style.backgroundColor = "red";
 }

 banner.onmouseover = function() {
 clearInterval(timer)
 }

 banner.onmouseout = function() {
 timer = setInterval(mover, 1000)
 }

 btnl.onclick = function(e) {
 movel();
 }
 btnr.onclick = function(e) {
 mover();
 }

 // 小圆点效果
 for(var i = 0; i < btns.length; i++) {
 btns[i].index = i;
 btns[i].onmouseover = function() {
 if(this.index == num) {
 return;
 } else {
 for(var i = 0; i < li.length; i++) {
 li[i].style.opacity = 0;
 btns[i].style.backgroundColor = "#ccc";
 }
 li[this.index].style.opacity = 1;
 btns[this.index].style.background="red";
 num=this.index;
 }
 }
 }
 </script>
 </body>

</html>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持极客世界。