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js学习总结_轮播图之渐隐渐现版(实例讲解)

2017-07-17 07:54 721 查看
具体代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
*{
margin:0;
padding:0;
font-size:14px;
-webkit-user-select:none;
}
ul,li{
list-style
}
img{
display: block;
border:none;
}
.banner{
position:relative;
width:1000px;
height:300px;
margin:0 auto;
overflow:hidden;
}
.banner .bannerInner{
width:100%;
height:100%;
background:url("../img/default.gif") no-repeat center center #e1e1e1;
}
.banner .bannerInner div{
position:absolute;
width:100%;
height:100%;
top:0;
left:0;
z-index:0;
opacity:0;
filter:alpha(opacity=0);
}
.banner .bannerInner img{
display:none;
width:100%;
height:100%s;
}
.banner .bannerTip{
position:absolute;
height:18px;
overflow:hidden;
right:20px;
bottom:20px;
z-index:10;
}
.banner .bannerTip li{
float:left;
margin-left:10px;
width:18px;
height:18px;
background:lightblue;
cursor:pointer;
border-radius:50%;
}
.banner .bannerTip li.bg{
background:red;
}
.banner a{
display:none;
position:absolute;
top:50%;
z-index:20;
margin-top:-22.5px;
width:30px;
height:45px;
background:url("../img/pre.png");
opacity:0.5;
filter:alpha(opacity=50);
}
.banner a:hover{
opacity:1;
filter:alpha(opacity=100);
}
.banner a.bannerLeft{
left:20px;
background-position:0 0;
}
.banner a.bannerRight{
right:20px;
background-position:-50px 0;
}
</style>
</head>
<body>
<div class='banner' id='banner'>
<div class='bannerInner'>
<div><img src="" alt="" trueImg="img/banner1.jpg"></div>
<div><img src="" alt="" trueImg="img/banner2.jpg"></div>
<div><img src="" alt="" trueImg="img/banner3.jpg"></div>
<div><img src="" alt="" trueImg="img/banner4.jpg"></div>
</div>
<ul class='bannerTip'>
<li class='bg'></li>
<li></li>
<li></li>
<li></li>
</ul>
<a href="javascript:;" rel="external nofollow" rel="external nofollow" class='bannerLeft'></a>
<a href="javascript:;" rel="external nofollow" rel="external nofollow" class='bannerRight'></a>
</div>
<script>
var banner = document.getElementById('banner');
var bannerInner = utils.firstChild(banner),bannerTip = utils.children(banner,"ul")[0],bannerLink = utils.children(banner,'a'),bannerLeft = bannerLink[0],bannerRight = bannerLink[1];
var divList = bannerInner.getElementsByTagName('div');
var imgList = bannerInner.getElementsByTagName('img');
var oLis = bannerTip.getElementsByTagName('li');
//1、Ajax读取数据
var jsonData = null;
~function(){
var xhr = new XMLHttpRequest;
xhr.open("get","json/banner.txt?_="+Math.random(),false);
xhr.onreadystatechange = function(){
if(xhr.readyState ===4 && /^2\d{2}$/.test(xhr.status)){
jsonData = utils.formatJSON(xhr.responseText)
}
}
xhr.send(null)
}()
//2、数据绑定
~function(){
var str = "",str2 = "";
if(jsonData){
for(var i = 0,len=jsonData.length;i<len;i++){
var curData = jsonData[i];
str+='<div><img src="" alt="" trueImg="'+curData['img']+'"></div>';
i===0?str2+="<li class='bg'></li>":str2+="<li></li>"
}
}
bannerInner.innerHTMl = str;
bannerTip.innerHTML = str2;
}()
//3、图片的延迟加载
window.setTimeout(lazyImg,500)
function lazyImg(){
for(var i = 0,len = imgList.length;i<len;i++){
~function(i){
var curImg = imgList[i];
var oImg = new Image;
oImg.src = curImg.getAttribute('trueImg');
oImg.onload = function(){
curImg.src = this.src;
curImg.style.display = block;
//只对第一张处理
if(i===0){
var curDiv = curImg.parentNode;
curDiv.style.zIndex = 1;
myAnimate(curDiv,{opacity:1},200);
}
oImg = null;
}
}(i)
}
}
//4、自动轮播
var interval = 3000,autoTimer = null,step = 0;
autoTimer = window.setInterval(autoMove,interval);
function autoMove(){
//当已经把最后一张展示完成后(step等于最后一张的索引),我们应该展示第一张，我们让step = -1,这样再经过一次累加，step就变为0，来展示第一张
if(step === jsonData.length-1){
step = -1
}
step++;
setBanner();
}
//实现轮播图切换效果的代码
function setBanner(){
//1、让step索引对应的那个DIV的zIndex的值为1，其他的zIndex为0
for(var i = 0,len = divList.length;i<len;i++){
var curDiv = divList[i];
if(i===step){
utils.css(curDiv,"zIndex",1)
//2、让当前的透明度从0变为1,当动画结束，我们需要让其他的div的透明度的值直接变为0
myAnimate(curDiv,{opacity:1},200,function(){
var curDivSib = utils.siblings(this);
for(var k = 0,len = curDivSib.length;k<len;k++){
utils.css(curDivSib[k],'opacity',0)
}
})
continue
}
utils.css(curDiv,"zIndex",0)
}
//实现焦点对其
for(i = 0,len = oLis.length;i<len;i++){
var curLi = oLis[i];
i === step?utils.addClass(curLi,"bg"):utils.removeClass(curLi,"bg");
}
}
//5、实现鼠标悬停停止自动轮播和离开在开启自动轮播
banner.onmouseover = function(){
window.clearInterval(autoTimer);
bannerLeft.style.display = bannerRight.style.display = "block"
}
banner.onmouseout = function(){
autoTimer = window.setInterval(autoMove,interval);
bannerLeft.style.display = bannerRight.style.display = "none"
}
//6、实现点击焦点切换
~function(){
for(var i = 0,len = oLis.length;i<len;i++){
var curLi = oLis[i];
curLi.index = i;
curLi.onclick = function(){
step = this.index;
setBanner();
}
}
}()
//7、实现左右切换
bannerRight.onclick = autoMove;
bannerLeft.onclick = function(){
if(step === 0){
step = jsonData.length;
}
step--;
setBanner();
}
</script>
</body>
</html>
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