JS: 图片轮播模板——左右移动，点击编码移动，自动轮播

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title></title>
  <style>
   * {
    margin: 0px;
    padding: 0px;
   }
   
   #stage {
    width: 500px;
    height: 300px;
    border: 3px solid black;
    margin: 100px;
    overflow: hidden;
    position: relative;
   }
   
   #banner {
    width: 3000px;
    height: 300px;
    background-color: rosybrown;
   }
   
   .items {
    width: 500px;
    height: 300px;
    color: white;
    font-size: 150px;
    text-align: center;
    line-height: 300px;
    float: left;
   }
   
   .btn-l,
   .btn-r {
    width: 50px;
    height: 300px;
    background-color: black;
    opacity: 0.5;
    color: white;
    font-size: 40px;
    line-height: 300px;
    text-align: center;
    position: absolute;
    top: 0px;
   }
   
   .btn-l {
    left: 0px;
   }
   
   .btn-r {
    right: 0px;
   }
   
   .btn-l:hover,
   .btn-r:hover {
    cursor: pointer;
    opacity: 0.2;
   }
   
   .points {
    position: absolute;
    bottom: 10px;
    left: 200px;
    /*background-color: orangered;*/
    width: 125px;
    height: 20px;
   }
   
   .dot {
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background-color: gainsboro;
    float: left;
    margin-right: 5px;
    cursor: pointer;
   }
   
   .active {
    background-color: red;
   }
  </style>
 </head>

<body>
  <div id="stage">
   <div class="btn-l">
    <</div>
     <div class="btn-r">></div>
     <div id="banner">
      <div class="items" style="">1</div>
      <div class="items" style="">2</div>
      <div class="items" style="">3</div>
      <div class="items" style="">4</div>
      <div class="items" style="">5</div>
      <div class="items" style="">1</div>
     </div>
     <div class="points">
      <div data="1" class="dot active"></div>
      <div data="2" class="dot"></div>
      <div data="3" class="dot"></div>
      <div data="4" class="dot"></div>
      <div data="5" class="dot"></div>
     </div>
   </div>
 </body>

</html>
<script>
// 取对象
 var btn_l = document.getElementsByClassName('btn-l')[0];
 var btn_r = document.getElementsByClassName("btn-r")[0];
 var banner = document.getElementById("banner");
 var dots = document.getElementsByClassName('dot');
// 定义变量
 var count = 1;
 var arr = [];
// 右侧按钮点击事件
 btn_r.onclick = function() {
  if(count < 6) {
   count++;
   arr.push(window.setInterval("move_left()", 20));
  } else if(count == 6) {
   count = 1;
   banner.style.marginLeft = 0 + 'px';
   count++;
   arr.push(window.setInterval("move_left()", 20));
  }
  for(var i = 0; i < dots.length; i++) {
   dots[i].setAttribute("class", "dot");
  }
  dots[count - 1].setAttribute("class", "dot active");
 }
// 左侧按钮点击事件
 btn_l.onclick = function() {
  if(count > 1) {
   count--;
   arr.push(window.setInterval("move_right()", 20));
  }else if(count == 1){
   count = 6;
   banner.style.marginLeft = -2500 + 'px';   
   count--;
   arr.push(window.setInterval("move_right()", 20));
  }
  
  for(var i = 0; i < dots.length; i++) {
   dots[i].setAttribute("class", "dot");
  }
  dots[count - 1].setAttribute("class", "dot active");
 }
// 向左移动
 function move_left() {
  if(banner.offsetLeft == (count - 1) * (-500)) {
   clear();
  } else {
   banner.style.marginLeft = banner.offsetLeft - 20 + "px";
  }

}
// 向右移动
 function move_right() {
  if(banner.offsetLeft == (count - 1) * (-500)) {
   clear();
  } else {
   banner.style.marginLeft = banner.offsetLeft + 20 + "px";
  }
 }
// 清除所有间隔执行
 function clear() {
  for(var x in arr) {
   window.clearInterval(arr[x]);
  }
 }
// 批量添加点击事件
 for(var j = 0; j < dots.length; j++) {
  dots[j].onclick = function() {
   count_s = this.getAttribute("data");
   if(count > count_s) {
    count = count_s;
    arr.push(window.setInterval("move_right()", 20));
   } else if(count < count_s) {
    count = count_s;
    arr.push(window.setInterval("move_left()", 20));
   }

for(var i = 0; i < dots.length; i++) {
    dots[i].setAttribute("class", "dot");
   }
   this.setAttribute("class", "dot active");
  }
 }
// 自动轮播
 function auto_move(){
  if(count < 6) {
   count++;
   arr.push(window.setInterval("move_left()", 20));
  } else if(count == 6) {
   count = 1;
   banner.style.marginLeft = 0 + 'px';
   count++;
   arr.push(window.setInterval("move_left()", 20));
  }
  for(var i = 0; i < dots.length; i++) {
   dots[i].setAttribute("class", "dot");
  }
  dots[count - 1].setAttribute("class", "dot active");
 } 
 window.setInterval("auto_move()",3000);
</script>