基於JavaScript實現簡單的輪播圖

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本文實例為大傢分享瞭JavaScript實現簡單的輪播圖的具體代碼，供大傢參考，具體內容如下

js輪播圖實現思路

1、先獲取元素 盒子 左右按鈕
2、鼠標經過 顯示/隱藏 左右側按鈕
3、動態生成小圓圈、 添加自定義屬性
4、小圓圈點擊事件 添加current類名
5、添加動畫事件 animate 等於 -索引號*focusWidth
6、克隆第一張圖片到最後面
7、添加右側/左側按鈕點擊事件
8、設置定時器 手動調用右側按鈕點擊事件

html代碼部分

<!DOCTYPE html>
<html lang="en">

<head>
 <meta charset="UTF-8">
 <meta http-equiv="X-UA-Compatible" content="IE=edge">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <link rel="stylesheet" href="css/index.css" >
 <script src="js/index.js"></script>
</head>

<body>
 <div class="focus">
 <a href="javascript:;" class="arrow_r">></a>
 <a href="javascript:;" class="arrow_l">
  <</a>
  <ul>
   <li>
   <a href=""><img src="images/focus.jpg" alt=""></a>
   </li>
   <li>
   <a href=""><img src="images/focus1.jpg" alt=""></a>
   </li>
   <li>
   <a href=""><img src="images/focus2.jpg" alt=""></a>
   </li>
   <li>
   <a href=""><img src="images/focus3.jpg" alt=""></a>
   </li>
  </ul>
  <ol class="circle">
  </ol>
 </div>
</body>

</html>

css樣式部分

* {
 padding: 0;
 margin: 0;
 }
 
 li {
 list-style: none;
 }
 
 img {
 border: 0;
 vertical-align: top;
 }
 
 a {
 text-decoration: none;
 }
 
 .focus {
 position: relative;
 width: 721px;
 height: 455px;
 margin: 100px auto;
 overflow: hidden;
 }
 
 .focus ul {
 position: absolute;
 top: 0;
 left: 0;
 width: 600%;
 }
 
 .focus ul li {
 float: left;
 }
 
 .arrow_r,
 .arrow_l {
 display: none;
 position: absolute;
 top: 50%;
 transform: translateY(-50%);
 width: 40px;
 height: 40px;
 line-height: 40px;
 text-align: center;
 font-size: 24px;
 background: rgba(0, 0, 0, .2);
 color: #fff;
 z-index: 1;
 }
 
 .arrow_r {
 right: 0;
 }
 
 .circle {
 position: absolute;
 bottom: 10px;
 left: 50px;
 }
 
 .circle li {
 float: left;
 width: 8px;
 height: 8px;
 border: 2px solid rgba(255, 255, 255, .5);
 border-radius: 50%;
 margin: 0 3px;
 cursor: pointer;
 }
 
 .current {
 background-color: #fff;
 }

javascript部分

window.addEventListener('load', function() {
 //獲取元素
 var focus = document.querySelector('.focus');
 var arrow_r = document.querySelector('.arrow_r');
 var arrow_l = document.querySelector('.arrow_l');
 var focusWidth = focus.offsetWidth;
 // 鼠標經過focus盒子 顯示/隱藏 左右側按鈕 暫停輪播
 focus.addEventListener('mouseenter', function() {
 arrow_r.style.display = 'block';
 arrow_l.style.display = 'block';
 clearInterval(timer);
 timer = null;
 });
 focus.addEventListener('mouseleave', function() {
 arrow_r.style.display = 'none';
 arrow_l.style.display = 'none';
 timer = setInterval(function() {
  //調用點擊事件
  arrow_r.click();
 }, 2000);
 });
 //動態生成小圓圈
 var ul = focus.querySelector('ul');
 var ol = focus.querySelector('.circle');
 for (var i = 0; i < ul.children.length; i++) {
 var li = document.createElement('li');
 li.setAttribute('index', i);
 ol.appendChild(li);
 //小圓圈點擊事件
 li.addEventListener('click', function() {
  for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
  }
  var index = this.getAttribute('index');
  num = index;
  circle = index;
  this.className = 'current';
  animate(ul, -index * focusWidth);
 })
 }
 ol.children[0].className = 'current';
 //克隆第一張圖片放到最後一張
 var fis = ul.children[0].cloneNode(true);
 ul.appendChild(fis);
 //右側按鈕點擊事件
 var num = 0;
 var circle = 0;
 arrow_r.addEventListener('click', function() {
 if (num === ul.children.length - 1) {
  ul.style.left = 0;
  num = 0;
 }
 num++;
 animate(ul, -num * focusWidth);
 circle++;
 if (circle === ul.children.length - 1) {
  circle = 0;
 }
 for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
 }
 ol.children[circle].className = 'current';
 });
 //左側按鈕點擊事件
 arrow_l.addEventListener('click', function() {
 if (num == 0) {
  num = ul.children.length - 1;
  ul.style.left = -num * focusWidth + 'px';

 }
 num--;
 animate(ul, -num * focusWidth);
 circle--;
 circle = circle < 0 ? ol.children.length - 1 : circle;
 // 調用函數
 circleChange();
 });
 //清除其餘小圓圈的current類名
 function circleChange() {
 for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
 }
 // 留下當前的小圓圈的current類名
 ol.children[circle].className = 'current';
 }
 //動畫函數
 function animate(obj, target, callback) {
 clearInterval(obj.timer);
 obj.timer = setInterval(function() {
  var step = (target - obj.offsetLeft) / 10;
  step = step > 0 ? Math.ceil(step) : Math.floor(step);
  if (obj.offsetLeft == target) {
  clearInterval(obj.timer);
  callback && callback();
  }
  obj.style.left = obj.offsetLeft + step + 'px';

 }, 15);
 }
 //自動輪播放輪播圖
 var timer = setInterval(function() {
 //調用點擊事件
 arrow_r.click();
 }, 2000);
});

以上就是本文的全部內容，希望對大傢的學習有所幫助，也希望大傢多多支持WalkonNet。

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