原生JS实现图片轮播 JS实现小广告插件

最近想用原生JS多实现一些小功能，现在写到博客里，大家可以借鉴，有问题欢迎指出。

轮播图

需求：

图片循环轮播，可点击左右切换，切换状态与<li>绑定，鼠标移入图片悬停，鼠标移出图片继续循环切换。

<!DOCTYPE html>
 
<html lang="en">
 
<head>
 
    <meta charset="UTF-8">
    <title>原生js轮播图片</title>
 
</head>
 
<style>
    .container{
        width: 100%;
        height: 500px;
        position: relative;
    }

    .content{
        width: 900px;
        height: 450px;
        position: relative;
        overflow: hidden; 
        border: 1px solid seagreen; 
        margin: 0 auto;
    }
 
    .slider-img{ 
        width: 900px; 
        height: 450px; 
        margin: 10px auto; 
    }
 
    .slider-img img{
        vertical-align: top;
        width: 800px;
        height: 400px;
        margin: 10px 50px;
        display: block;
 
    }
 
    .left{
        margin-top: -300px;
        margin-left: 50px;
        width: 100px;
        height: 100px;
    }
 
    .left img,.right img{
        width: 100px;
        height: 100px;
    }
 
    .right{
        margin-top: -100px;
        margin-right: 50px;
        float: right;
        width: 100px;
        height: 100px;
 
    }
 
 
 
    .dot{
        position: relative;
        top: 23%;
        left: 43%;
        width: 50%;
    }
 
    .dotul{
        width: 450px;
    }

    .dotul li{ 
        width: 20px; 
        height: 20px;
        background-color: seagreen;
        list-style: none;
        float: left;
        border-radius: 20px; 
        margin-left: 15px; 
        z-index: 999; 
        cursor: pointer; 
    }
 
    .active{
        background-color: orangered !important;
    }
 
 
 
</style>
 
<body>
 
    <div class="container" id="container">
 
        <div class="content" id="content">
            <div class="slider-img" id="slider" >
                  <a href="javascript:;" rel="external nofollow"  >
                    <img src="./img/88.jpg" alt="" id="img">
                </a>
            </div>
 
        </div>
        <div class="btn">
            <div class="left" id="left">
                <a href="%20###" rel="external nofollow"  rel="external nofollow"  ><img src=""></a>
            </div>
 
            <div class="right" id="right">
                <a href="%20###" rel="external nofollow"  rel="external nofollow"  ><img src=""></a>
            </div>
        </div>
 
        <div class="dot">
            <ul id="ul" class="dotul">
                <li class="active"></li>
                <li></li>
                <li></li>
               <li></li>
            </ul>
        </div>
</div>

js代码，使用时记得在html里引入JS。

var container = document.getElementById("container"); 
var content = document.getElementById("content");
var slider = document.getElementById("slider");
var img = document.getElementById("img");
var ul = document.getElementById("ul"); 
var li = document.getElementsByTagName("li"); 
var left = document.getElementById("left"); 
var right = document.getElementById("right"); 
var num = 0;
var timer = null;    
var picList = ["./img/88.jpg","./img/are.jpg","./img/family.jpg","./img/one.jpg"];
//将li与list下标对应
 

    //设置展示图片的方法，展示时，li的圆点与图片绑定在一起
    ShowPicture = function() {
       img.src = picList[num];
       for(var i = 0 ; i < li.length;i++) {
           li[i].className = '';
       }
       li[num].className = 'active';
    }
  
    //左点击，如果已经是第一张了就返回最后一张

    left.onclick = function() {
        num--;
        if(num < 0) {
           num = picList.length-1;
        }
        ShowPicture();
    }
  

    //右点击，若已经是最后一张返回第一张
    right.onclick = function() {
        num++;
        if(num >= picList.length) {   //3
            num = 0;
        }
        ShowPicture();
    }
    
     //实现点击圆点跳转对应图片，将li与list下标对应list.index=li.index
   
     for(var i = 0; i < picList.length ; i++) {
         li[i].index = i;
         li[i].onclick = function() {
             num = this.index;
             ShowPicture();
         }
     }

    //自动轮播图片，每次调用要记得清除定时器，并在调用后回归定时器，防止时间差越变越大

    autoChange = function() {
        clearInterval(timer);
        timer = setInterval(() => {
            num++;
            num %= picList.length;
            ShowPicture();
        }, 3000);
        return timer;
    }
    window.onload = autoChange;

   
    //事件
    img.onmouseover = function() {
        clearInterval(timer);
    }
    img.onmouseleave = autoChange;

广告插件

需求：页面加载结束后弹出广告，广告轮播展示，鼠标移入悬停，移出继续展示，点X可删除。

<div id="win">
        <img id = "img" />
        <button id = "ad_btn">X</button>  
        //我这是练习，叉号用的X替代，自己做项目加入时可以换成Icon
</div>

//页面加载结束弹出广告，广告切换展示，点击X可删除,
var ad = document.getElementById('win');
var img = document.getElementById('img');
var ad_btn  = document.getElementById('ad_btn');
var timer;
window.onload = function () {
    // clearInterval(timer);
    timer = setTimeout(() => {
            ad.style.display = 'block';  
        }, 2000);
        change();
}

var count=0;
var num = 0;
var imgTimer = null;
//picture srcList
var picList = ['../img/88.jpg','../img/one.jpg','../img/family.jpg','../img/are.jpg'];
function change() {
    clearInterval(imgTimer)
    imgTimer = setInterval(() => {
       if(count === picList.length) {
           count = 0;
           resetShow();
       } else {
           startShow();
       }
       count++;          
   }, 3000);
}
function resetShow() {
    img.src = picList[0];
    num = 0;
    startShow();
}

function startShow() {
    if(num < picList.length) {
        img.src = picList[num++];
    } else {
        resetShow();
    }
   
}


ad_btn.addEventListener('click' , (e)=>{
    ad.style.display = 'none';
    clearTimeout(timer)
});

ad.addEventListener('mouseover' , ()=>{
    clearInterval(imgTimer);
})
ad.onmouseleave = function() {
    change();
}

实现展示：

原生JS实现图片轮播 JS实现小广告插件