基于JavaScript实现简单的轮播图
本文实例为大家分享了JavaScript实现简单的轮播图的具体代码，供大家参考，具体内容如下
js轮播图实现思路1、先获取元素 盒子 左右按钮2、鼠标经过 显示/隐藏 左右侧按钮3、动态生成小圆圈、 添加自定义属性4、小圆圈点击事件 添加current类名5、添加动画事件 animate 等于 -索引号*focusWidth6、克隆第一张图片到最后面7、添加右侧/左侧按钮点击事件8、设置定时器 手动调用右侧按钮点击事件
html代码部分<!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='https://www.haobala.com/bcjs/css/index.css' > <script src='https://www.haobala.com/bcjs/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='https://www.haobala.com/bcjs/14158.html'><img src='https://www.haobala.com/bcjs/images/focus.jpg' alt=''></a> </li> <li> <a href='https://www.haobala.com/bcjs/14158.html'><img src='https://www.haobala.com/bcjs/images/focus1.jpg' alt=''></a> </li> <li> <a href='https://www.haobala.com/bcjs/14158.html'><img src='https://www.haobala.com/bcjs/images/focus2.jpg' alt=''></a> </li> <li> <a href='https://www.haobala.com/bcjs/14158.html'><img src='https://www.haobala.com/bcjs/images/focus3.jpg' alt=''></a> </li> </ul> <ol class='circle'> </ol> </div></body></html>
css样式部分
* { 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() { //获取元素 var focus = document.querySelector(’.focus’); var arrow_r = document.querySelector(’.arrow_r’); var arrow_l = document.querySelector(’.arrow_l’); var focusWidth = focus.offsetWidth; // 鼠标经过focus盒子 显示/隐藏 左右侧按钮 暂停轮播 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() { //调用点击事件 arrow_r.click(); }, 2000); }); //动态生成小圆圈 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); //小圆圈点击事件 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’; //克隆第一张图片放到最后一张 var fis = ul.children[0].cloneNode(true); ul.appendChild(fis); //右侧按钮点击事件 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’; }); //左侧按钮点击事件 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; // 调用函数 circleChange(); }); //清除其余小圆圈的current类名 function circleChange() { for (var i = 0; i < ol.children.length; i++) { ol.children[i].className = ’’; } // 留下当前的小圆圈的current类名 ol.children[circle].className = ’current’; } //动画函数 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); } //自动轮播放轮播图 var timer = setInterval(function() { //调用点击事件 arrow_r.click(); }, 2000);});
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持好吧啦网。
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