原生js+css3实现图片自动切换，图片轮播
运用CSS3transition及opacity属性 制作图片轮播动画
自己这两天根据用js来控制触发CSS3中transition属性，从而写出来的以CSS3动画为基础，js控制过程的图片轮播
运用css3的opacity透明度属性和transition动画过度属性，用js对过程加以控制，也实现了js对CSS3中transition动画的触发
实例链接地址：http://pspgbhu.github.io/opacity
今天突然发现这个代码有问题，主要出在html/css上，问题主要是由于使用了position：absolute定位，同时banner这个div中又没有其他元素，因此这个div就无法被正确的撑开，为我们的页面布局带来了困扰。
再其次的问题是，这个轮播图主要意图是用于页面顶部的巨大的横幅广告，但是在写代码时并没有考虑到面对不同分辨率情况下的展现效果，因此还有许多改良的空间。
想了想还是不把之前有问题的代码删掉了，正确代码在最后面
这是之前有问题的代码:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>图片自动切换 图片轮播</title>
<style type="text/css">
/*注意 第一张图片z-index值是5，后面的图片值为1*/
*{margin: 0;padding: 0;}
.banner {
width: 1920px;
height: 493px;
position: relative;
}
.banner_slide_1 {
position: absolute;
top: 0;
left: 0;
display: block;
transition: opacity 0.5s;
opacity: 1;
z-index: 5;
}
.banner_slide_2 {
position: absolute;
top: 0;
left: 0;
display: none;
transition: opacity 0.5s;
opacity: 0;
z-index: 1;
}
.banner_slide_3 {
position: absolute;
top: 0;
left: 0;
display: none;
transition: opacity 0.5s;
opacity: 0;
z-index: 1;
}
</style>
<script type="text/javascript">
window.onload=function bannerSlide() {
var i = 0;
var banner = new Array//将图片创建为一个数组
banner[0] = document.getElementById("banner1");
banner[1] = document.getElementById("banner2");
banner[2] = document.getElementById("banner3");
sli = setInterval(slide, 5000); //轮播间隔时间
function slide() {
if (i == banner.length - 1) {
banner[0].style.display = "block";
banner[0].style.opacity = "1";
banner[i].style.opacity = "0";
setTimeout(function() {
banner[i].style.display = "none";
banner[i].style.zIndex = "1";
banner[0].style.zIndex = "5";
i = 0;
}, 500)
} else {
banner[i + 1].style.display = "block";
banner[i + 1].style.opacity = "1";
banner[i].style.opacity = "0";
setTimeout(function() {
banner[i + 1].style.zIndex = "5";
banner[i].style.display = "none";
banner[i].style.zIndex = "1";
i++;
}, 500)
}
}
}
</script>
</head>
<body>
<div class="banner">
<div class="banner_slide_1" id="banner1"><img src="img/banner.jpg" alt="" /></div>
<div class="banner_slide_2" id="banner2"><img src="img/banner02_02.jpg" /></div>
<div class="banner_slide_3" id="banner3"> <img src="img/banner3.jpg" /></div>
</div>
</body>
</html>
以下为改良后的代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style type="text/css">
*{padding: 0;margin: 0;
}
.banner {
width: 100%;
min-width: 1200px;
height: 488px;
overflow: hidden;
}
.banner_index {
position: relative;
}
.banner_slide_1 {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
display: block;
transition: opacity 0.5s;
opacity: 1;
z-index: 5;
background: url(img/banner.jpg) no-repeat;
background-position: center 0;
}
.banner_slide_2 {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
display: none;
transition: opacity 0.5s;
opacity: 0;
z-index: 1;
background: url(img/banner02_02.jpg) no-repeat;
background-position: center 0;
}
.banner_slide_3 {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
display: none;
transition: opacity 0.5s;
opacity: 0;
z-index: 1;
background: url(img/banner3.jpg) no-repeat;
background-position: center 0;
}
</style>
<script type="text/javascript">
window.onload=function bannerSlide() {
if (!document.getElementById) return false;
if (!document.getElementsByTagName) return false;
if (!document.getElementById("bannerBox")) return false;
var i = 0;
var box = document.getElementById("bannerBox");
var banner = box.getElementsByTagName("div");
sli = setInterval(slide, 4000); //轮播间隔时间
function slide() {
if (i == banner.length - 1) {
banner[0].style.display = "block";
banner[0].style.opacity = "1";
banner[i].style.opacity = "0";
setTimeout(function() {
banner[i].style.display = "none";
banner[i].style.zIndex = "1";
banner[0].style.zIndex = "5";
i = 0;
}, 500) //动画过渡时间，搭配CSS使用
} else {
banner[i + 1].style.display = "block";
banner[i + 1].style.opacity = "1";
banner[i].style.opacity = "0";
setTimeout(function() {
banner[i + 1].style.zIndex = "5";
banner[i].style.display = "none";
banner[i].style.zIndex = "1";
i++;
}, 500)
}
}
}
</script>
</head>
<body>
<div id="bannerBox" class="banner banner_index">
<div class="banner_slide_1" id="banner1"></div>
<div class="banner_slide_2" id="banner2"></div>
<div class="banner_slide_3" id="banner3"></div>
</div>
</body>
</html>
作者博客：[pspgbhu](http://ghosertblog.github.com)
作者GitHub：https://github.com/pspgbhu
欢迎转载，但请注明出处，谢谢！
