原生JS实现轮播图核心功能与定时器瑕疵分析

核心代码结构与样式定义

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title></title>
  <style type="text/css">
   #banner{
    width: 716.8px;
    height: 537.6px;
    background-color: aquamarine;
    margin: 100px auto;
    position: relative;
    font-size: 0px;  /*清除img图片间的回车符产生的间隔*/
    overflow: hidden;
   }
   #banner #bannerImg{
    width: 100%;
    position: absolute;
    top: 0px;
    left: 0px;
    white-space: nowrap; /*使这个图片能一行显示*/
    transition:all 1s linear;
   }
   #banner #bannerImg .img{
    width: 100%;
   }
   #banner #bannerButton{
    font-size: 16px;
    color: white;
    position: absolute;
    bottom: 10px;
    left: 20px;
   }
   #banner #bannerButton .Button{
    border-radius: 9px;
    border: none;
    outline: none;
    cursor: pointer;
    background-color: #7FFFD4;
   }
   #banner #bannerButtonAside .div1{
    position: absolute;
    right: 10px;
    top: 50%;
    margin-top: -32px;
    cursor: pointer;
   }
   
   #banner #bannerButtonAside .div2{
    position: absolute;
    left: 10px;
    top: 50%;
    margin-top: -32px;
    cursor: pointer;
   }
  </style>
 </head>
 <body>
  <!--实现 左右按钮，1234，自动滑动，鼠标停上显示小手不动 暂停。-->
  <section id="banner" onmouseover="changeStop()" onmouseout="changeStart()">
   
   <!--以下是我们的banner图-->
   <div id="bannerImg">
    <img class="img" src="../img/c95d7b9676ae739cccfc55457b93fe9c.jpg"/>
    <img class="img" src="../img/5f5bdebddd8f1d276aeac8af5f8fa38d.jpg"/>
    <img class="img" src="../img/5f5e5c091ecb0525fc8204f200670dd9.jpg"/>
    <img class="img" src="../img/efa11cad9094f951061ee21324277efe.jpg"/>
    <img class="img" src="../img/0b54c021bd4384c168d835dfc0908018.jpg"/>
    <img class="img" src="../img/25d10d413faca3bdd7e2d88667f4298f_看图王.jpg"/>
    <img class="img" src="../img/c95d7b9676ae739cccfc55457b93fe9c.jpg"/> <!--第7张与第一张为同一图片，消除图片切换间断-->
   </div>
   
   <!--以下是我们左下方的banner图按钮-->
   <div id="bannerButton">
    <button class="Button" onclick="buttonChange(0)">1</button>
    <button class="Button" onclick="buttonChange(1)">2</button>
    <button class="Button" onclick="buttonChange(2)">3</button>
    <button class="Button" onclick="buttonChange(3)">4</button>
    <button class="Button" onclick="buttonChange(4)">5</button>
    <button class="Button" onclick="buttonChange(5)">6</button>
   </div>
   
   <!--以下是我们左右两个方向按钮-->
   <div id="bannerButtonAside">
    <div class="div1" onclick="asideChange(1)">
     <img src="../img/forword.png"/>
    </div>
    <div class="div2" onclick="asideChange(0)">
     <img src="../img/back.png"/>
    </div>
   </div>
  </section>
 </body>
 
 <script type="text/javascript">
  var bannerImg=document.getElementById("bannerImg"); /*取出img容器的节点*/
  var Button=document.getElementsByClassName("Button"); /*取出所有的button按钮*/
  var num=0;  /*定义全局变量num,控制banner的切换次序*/
  var aaa=0;  /*定义一个全局变量,用来取定时器函数,并在没有鼠标事件的时候清除定时器*/
   
  /*通过定时器实现banner图的每3000毫秒切换一次的效果的changeStart()函数*/
  function changeStart(){
    aaa=setInterval(function(){
    if (num<=6) {
     bannerImg.style.transition="all 1s linear";
     bannerImg.style.left=(-716.8)*(num)+"px";
     num++;
    }else{
     bannerImg.style.transition="all 0s linear";  /*消除num=0时,bannerImg移动的过渡效果*/
     num=0;
     bannerImg.style.left=(-716.8)*(num)+"px";
     
    }
    console.log("哈哈哈继续");
   },3000)
  }
  changeStart();
  
  /*以下是当鼠标悬浮在banner图上时,图片停止自动切换的changeStop()函数*/
  function changeStop(){
   clearInterval(aaa); 
   console.log("停止他");
  }
  
  /*以下是点击按钮实现对应banner图切换的change()函数*/
  function buttonChange(Num){
   num=Num+1;
   bannerImg.style.transition="all 0s linear";
   bannerImg.style.left=(-716.8)*(Num)+"px";
  }
  
  /*以下是点击左右两个按钮实现banner图切换的buttonChange()函数*/
  function asideChange(x){ /*通过传递形参x,判断往左/往右切换banner图*/
   if (num!=6&&x==1) {
    num++;
   }else if(num==6&&x==1){
    num=0;
   }else if(num!=0&&x==0){
    num--;
   }
   else if(num==0&&x==0){
    num=5;
   }
   bannerImg.style.transition="all 0s linear";
   bannerImg.style.left=(-716.8)*(num)+"px";
  }
 </script>
</html>