js鼠标事件(一)实现banner的轮播效果

一.要实现的效果

1.点击左右可切换图片
2.点击小圆点 可切换图片

二.效果图

js鼠标事件(一)实现banner的轮播效果_第1张图片

三.代码

1.css

<style type="text/css">
body,img,span,ul,li{margin: 0;padding: 0;}
#div1{width: 600px;height: 350px;margin: 150px auto;border: 10px solid #eee;position: relative;}
img{width: 600px;height: 350px;}
span{display: inline-block;position: absolute;width: 50px;height: 50px;border-radius: 25px;background:rgba(0,0,0,.3); font-size: 30px;line-height: 50px;text-align: center;cursor: pointer;color: white;}
span:hover{background:rgba(255,255,255,.5);color:black;transform:scale(1.3);}
span#L{left: 10px;top: 150px;}
span#R{right: 10px;top: 150px;}
#div1 #ul{position: absolute;bottom: 10px;left: 250px;width: 125px;height: 20px;}
#div1 #ul li{list-style: none;float: left;height: 20px;width: 20px;border-radius: 10px;background:rgba(255,255,255,.5); margin-right: 5px;cursor: pointer;}
#div1 #ul .active{background:rgba(0,0,0,.5);}
style>

2.html

<body>
    <div id="div1">
        <img src="" alt="">
        <span id="L"><span>
        <span id="R">>span>
        <ul id="ul">
          <li>li>
          <li>li>
          <li>li>
          <li>li>
          <li>li>
        ul>
    div>
body>

3.js

<script type="text/javascript">
window.onload=function(){
    var div1=document.getElementById('div1');
    var oImg=div1.getElementsByTagName('img')[0];
    var spanL=document.getElementById('L');
    var spanR=document.getElementById('R');
    var oUl=document.getElementById('ul');
    var oLi=oUl.getElementsByTagName('li');
    var arrImg=['img2/1.jpg','img2/2.jpg','img2/3.jpg','img2/4.jpg','img2/5.jpg'];
    var num=0;
    var oldLi=0;

    function fn(num) {
        oImg.src=arrImg[num];
    }
    fn(0);
    function fnLi(num){
        oLi[oldLi].className='';
       oLi[num].className='active';
       oldLi=num;
    }
    fnLi(0);
    /*点击左右span图片切换*/
    /*点击左右span时li切换*/
    spanL.onclick=function(){
        if (num<1) {
           num=arrImg.length-1;
           fn(num);
           fnLi(num);
        }else{
           num--;
           fnLi(num);
           fn(num);
        }        
    }
    spanR.onclick=function(){
        if (num==arrImg.length-1) {
           num=0;
           fn(num);
           fnLi(num);
        }else{
           num++;
           fnLi(num);
           fn(num);
        }        
    }
    /*点击li实现图片切换*/
    for (var i = 0; i < oLi.length; i++) {
        oLi[i].index=i;
        oLi[i].onclick=function(){
            fn(this.index);
            fnLi(this.index);
        }
    }
}
script>

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