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原生js实现轮播图特效

轮播图也称为焦点图,是网页中比较常见的网页特效。

功能需求:

"htmlcode">

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

<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <link rel="stylesheet" href="css/index.css" rel="external nofollow" >
 <script src="/UploadFiles/2021-04-02/animate.js">

css文件:

* {
 margin: 0;
 padding: 0;
 outline: none;
}
.box {
 overflow: hidden;
 position: relative;
 height: 455px;
 width: 721px;
 background-color: pink;
 margin: 50px auto;
}
.box ul {
 position: absolute;
 top: 0;
 left: 0;
 width: 600%;
}
.box ul li {
 list-style: none;
 float: left;
}
.box ol {
 position: absolute;
 bottom: 10px;
 left: 100px;
 background-color: rgba(255, 255, 255, .3);
 border-radius: 8px;
 list-style: none;
 height: 10px;
 padding: 2px 5px;
}
.box ol li {
 cursor: pointer;
 float: left;
 height: 8px;
 width: 8px;
 border: 1px solid #fff;
 border-radius: 50%;
 margin: 0 5px;
}
.arr-l,
.arr-r {
 display: none;
 color: #fff;
 cursor: pointer;
 position: absolute;
 height: 40px;
 width: 30px;
 background-color: rgba(0, 0, 0, .3);
 line-height: 40px;
 text-align: center;
}
.arr-l {
 top: 50%;
 left: 0;
 transform: translateY(-50%);
}
.arr-r {
 right: 0;
 top: 50%;
 transform: translateY(-50%);
}
.current {
 background-color: #fff;
}

动画实现js文件animate.js:

function animate(obj, target, callback) {
 clearInterval(obj.timer);
 obj.timer = setInterval(function () {
 if (target - obj.offsetLeft > 0) {
  var step = Math.ceil((target - obj.offsetLeft) / 10);
 } else {
  var step = Math.floor((target - obj.offsetLeft) / 10);
 }

 if (obj.offsetLeft == target) {
  clearInterval(obj.timer);
  callback && callback();
 }
 obj.style.left = obj.offsetLeft + step + 'px';
 }, 15)
}

index.js:

window.addEventListener('load', function () {
 var arrl = this.document.querySelector('.arr-l');
 var arrr = this.document.querySelector('.arr-r');
 var box = this.document.querySelector('.box');
 var boxWidth = box.offsetWidth;
 box.addEventListener('mouseenter', function () {
 arrl.style.display = 'block';
 arrr.style.display = 'block';
 clearInterval(timer);
 timer = null;
 })
 box.addEventListener('mouseleave', function () {
 arrl.style.display = 'none';
 arrr.style.display = 'none';
 timer = setInterval(function () {
  arrr.click();
 }, 2000);
 });


 var ul = box.querySelector('ul');
 var ol = box.querySelector('ol');
 for (var i = 0; i < ul.children.length; i++) {
 var li = document.createElement('li');
 li.setAttribute('data-index', i);
 ol.appendChild(li);
 ol.children[0].className = 'current';
 li.addEventListener('click', function () {
  for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
  }

  this.className = 'current';
  var dateindex = this.getAttribute('data-index');
  num = dateindex;
  circle = dateindex;
  animate(ul, -dateindex * boxWidth);
 });
 }

 var first = ul.children[0].cloneNode(true);
 ul.appendChild(first);

 var num = 0;
 var circle = 0;
 var flag = true;
 arrr.addEventListener('click', function () {
 if (flag) {
  flag = false;
  if (num == ul.children.length - 1) {
  ul.style.left = 0;
  num = 0;
  }
  num++;
  animate(ul, -num * boxWidth, function () {
  flag = true;
  });
  circle++;
  if (circle == ol.children.length) {
  circle = 0;
  }
  circleChange();
 }

 });
 arrl.addEventListener('click', function () {
 if (flag) {
  flag = false;
  if (num == 0) {
  num = ul.children.length - 1;
  ul.style.left = -num * boxWidth + 'px';
  }
  num--;
  animate(ul, -num * boxWidth, function () {
  flag = true;
  });
  circle--;
  if (circle < 0) {
  circle = ol.children.length - 1;
  }
  circleChange();

 }
 });
 function circleChange() {
 for (var i = 0; i < ol.children.length; i++) {
  ol.children[i].className = '';
 }
 ol.children[circle].className = 'current';
 }

 var timer = setInterval(function () {
 arrr.click();
 }, 2000);
})

注意事项

引用两个js文件时,animate.js要在index.js之前引用,因为index.js中要用到animate.js里的函数。

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