原生JS实现轮播图(3种方法)

最近在巩固JS基础知识，顺手敲了个轮播图，它有3种换图方法。

自动换图 (设置定时器每隔2s换一张图)
点击左右箭头换图
点击小圆点换图

代码如下

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <link rel="stylesheet" href="font.css">
    <title>Document</title>
    <style>
    *{
        margin: 0;
        padding: 0;
        list-style-type: none;
        text-decoration: none;
    }
    #fade{
        width: 500px;
        height: 500px;
        margin: 0 auto;
        position: relative;
    }
    .now-left{
        position: absolute;
        top: 45%
    }
    .now-right{
        position: absolute;
        top: 45%;
        left:93%;
    }
    .ul_dian{
        position: absolute;
        top: 90%;
        left: 38%;
    }
    .ul_dian li{
        float: left;
    }
    </style>
</head>
<body>
    <center><h2>轮播图</h2></center>
    <div id="fade">
        <img src="img/1.jpg" width="100%" height="100%" id="lunbo">
        <i class='iconfont icon-jiantouzuo now-left' id="left"></i>
        <i class='iconfont icon-jiantouyou now-right' id="right"></i>
        <ul class="ul_dian">
            <li class='iconfont icon-yuandianzhong '></li>
            <li class='iconfont icon-yuandianzhong '></li>
            <li class='iconfont icon-yuandianzhong '></li>
            <li class='iconfont icon-yuandianzhong'></li>
        </ul>
    </div>
    <script>
        var lb = document.getElementById("lunbo")
        var num=1;


        // 自动换图
        setInterval(function(){
            num++;
            if(num == 5){
                num = 1;     
            }
            lb.src="img/"+num+".jpg" 
            // console.log(num)
        },3000)
        var left = document.getElementById("left")
        var right = document.getElementById("right")

        // 点击左箭头换图
        left.onclick=function(){
            num--;
            if(num == 0){
                num = 1;     
            }
            lb.src="img/"+num+".jpg" 
   
        }

        // 点击右键换箭头
        right.onclick=function(){
            num++;
            if(num == 5){
                num = 4;     
            }
            lb.src="img/"+num+".jpg" 
        }


        // 点击圆点换图
        var allLi = document.getElementsByTagName('ul')[0].getElementsByTagName("li");
        for(var i = 0 ; i < allLi.length ; i++){
            // 给每个li元素赋值，每循环一次，i+1;
            allLi[i].index = i;
            allLi[i].onclick=function(){
                // li的索引是从0开始的，所以要+1
                var num = this.index+1;
                lb.src="img/"+num+".jpg" 
            }   
        }
    </script>
</body>
</html>

效果图

在这里插入图片描述

来源：CSDN

作者：HaiJun_Aion

链接：https://blog.csdn.net/HaiJun_Aion/article/details/86661592

标签

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js代码

轮播