1.  <div class="content">
    2.         <div id="list">
    3.             <img src="images/01.png" alt="">
    4.             <img src="images/02.png" alt="">
    5.             <img src="images/03.png" alt="">
    6.             <img src="images/04.png" alt="">
    7.             <img src="images/05.png" alt="">
    8.         </div>
    9.         <button id="prev"></button>
    10.         <button id="next"></button>
    11.         <div id="btns">
    12.             <span class="current"></span>
    13.             <span></span>
    14.             <span></span>
    15.             <span></span>
    16.             <span></span>
    17.         </div>
    18.     </div>
     <script>
        var prev=document.getElementById("prev");
        var next=document.getElementById("next");
        var lists=document.querySelectorAll("#list>img");
        var icons=document.querySelectorAll("#btns>span")
        var index=0;   //记录下标
        next.onclick=function(){
            index++;
            if(index>4){
                index=0;
            }
            show(index)
        }
        prev.onclick=function(){
            index--;
            if(index<0){
                index=4;
            }
            show(index)
        }
        /* 重置下标 */
        for(let i=0;i<icons.length;i++){
            icons[i].index=i;
            icons[i].onclick=function(){
                let currentIndex=this.index;
                show(currentIndex)
            }
        }

        /* 封装 */
        function show(index){
            for(let i=0;i<lists.length;i++){
                lists[i].style.display="none"
            }
            lists[index].style.display="block"

            for(let i=0;i<icons.length;i++){
                icons[i].classList.remove("current")
            }
            icons[index].classList.add("current")
        }
    </script>