中信建设有限责任公司招投标网站搜索引擎优化
实现图片轮播效果，打开页面，每隔3秒切换至下一张图片；光标移入数字时，播放相应图片。
思路：
（1）获取需要轮播的图片和展示的div。
（2）使用animate设置left值，每次移动宽度为展示div的宽度。
（3）播放图片时，对应数字应用红色背景样式，其他数字移除该样式。
效果：
代码：
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>Document</title><style>* {margin: 0;padding: 0;}img {width: 800px;height: 400px;}.banner {width: 800px;height: 400px;border: 1px solid black;margin: 50px auto;overflow: hidden;cursor: pointer;position: relative;}.banner .slide {width: 4800px;height: 400px;position: absolute;left: -600px;}.banner .slide .pic {width: 800px;height: 400px;line-height: 400px;text-align: center;float: left;font-size: 72px;color: white;}.banner .numbers {width: 150px;height: 30px;position: absolute;bottom: 1%;left: 85%;margin-left: -50px;z-index: 2;}.banner .numbers .number {width: 20px;height: 20px;float: left;margin: 5px 6px;cursor: pointer;background-color: white;color: black;text-align: center;border: 1px solid red;}.banner .numbers .on {background-color: red;color: #fff;font-weight: bolder;}</style></head><body><div class="banner"><div class="slide"><div class="pic"><img src="./4.png"></div><div class="pic"><img src="./1.png"></div><div class="pic"><img src="./2.png"></div><div class="pic"><img src="./3.png"></div><div class="pic"><img src="./4.png"></div><div class="pic"><img src="./1.png"></div></div><div class="numbers"><span class="number on">1</span><span class="number">2</span><span class="number">3</span><span class="number">4</span></div></div><script src="jquery-1.12.4.js" type="text/javascript" charset="utf-8"></script><script type="text/javascript">var index = 1; var timer = null;var size = $('.slide').children().size();var picWidth = $('.pic').width();$('.banner').mouseover(function() {clearInterval(timer);});$('.banner').mouseleave(function() {autoSlide();});$('.slide').mouseleave();function autoSlide() {timer = setInterval(function() {index++; changeImg();changeNums();}, 3000); };function changeImg() {var slideWidth = -1 * picWidth * index; $('.slide').animate({'left': slideWidth + 'px'}, 500);if (index >= size - 1) {$('.slide').animate({'left': -picWidth + 'px'}, 0);index = 1;}if (index < 1) {$('.slide').animate({'left': -(size - 2) * picWidth + 'px'}, 0);index = size - 2;}}function changeNums() {$('.number').eq(index - 1).addClass('on').siblings().removeClass('on');}$('.number').mouseover(function(event) {var target = event.target;index = $(target).index() + 1;changeImg();changeNums();});</script></body>
</html>