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Implementation of Simple Carousel Map Based on JavaScript

  • 2021-11-01 01:44:24
  • OfStack

In this paper, we share the specific code of JavaScript to realize simple carousel diagram for your reference. The specific contents are as follows

Implementation idea of js carousel map

1. Get the left and right buttons of the element box first
2. The mouse passes through the show/hide left and right buttons
3. Dynamically generate small circles and add custom attributes
4. Click on the small circle event to add current class name
5. Add animation event animate equals-index number * focusWidth
6. Clone the first picture to the back
7. Add right/left button click events
8. Set the timer to manually call the right button click event

html code section 


<!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 Style Section 


* {
 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 Part 


window.addEventListener('load', function() {
 // Get Element 
 var focus = document.querySelector('.focus');
 var arrow_r = document.querySelector('.arrow_r');
 var arrow_l = document.querySelector('.arrow_l');
 var focusWidth = focus.offsetWidth;
 //  Mouse passing focus Box   Display / Hide   Left and right side buttons   Suspend carousel 
 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() {
  // Call click event 
  arrow_r.click();
 }, 2000);
 });
 // Dynamically generate small circles 
 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);
 // Small circle click event 
 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';
 // Clonidy 1 Put the picture at the end 1 Zhang 
 var fis = ul.children[0].cloneNode(true);
 ul.appendChild(fis);
 // Right button click event 
 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';
 });
 // Left button click event 
 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;
 //  Call function 
 circleChange();
 });
 // Object that clears the remaining small circles current Class name 
 function circleChange() {
 for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
 }
 //  That leaves the current small circle current Class name 
 ol.children[circle].className = 'current';
 }
 // Animation function 
 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);
 }
 // Automatic carousel carousel 
 var timer = setInterval(function() {
 // Call click event 
 arrow_r.click();
 }, 2000);
});
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