javaScript实现轮播图效果（逆战总结）
1.HTML代码
<div id="wrap">
<img src="images/1.jpg" alt="" class="on">
<img src="images/2.jpg" alt="">
<img src="images/3.jpg" alt="">
<img src="images/4.jpg" alt="">
<div class="btn">
<span class="active"></span>
<span></span>
<span></span>
<span></span>
</div>
<i class="left" id="prev"></i>
<i class="right" id="next"></i>
</div>
2.css代码
#wrap{
position: relative;
width:590px;
height: 470px;
}
#wrap img{
position: absolute;
top: 0;
left: 0;
/*display: none;*/
opacity: 0;
}
#wrap .on{
/*display: block;*/
transition: 2s;
opacity: 1;
}
.btn {
position: absolute;
bottom: 20px;
left: 50%;
margin-left: -44px;
}
.btn span{
float: left;
width: 8px;
height: 8px;
border:2px solid rgba(255,255,255,0.4);
border-radius: 5px;
margin-right: 10px;
}
.btn .active{
background: white;
cursor: pointer;
}
.left,.right{
display: block;
width: 37px;
height: 53px;
position: absolute;
top: 50%;
margin-top: -27px;
cursor: pointer;
}
.left{
background: url("images/arrow.png") left top;
}
.right{
background: url("images/arrow.png") left -53px;
right: 0;
}
3.js代码
window.onload = function () {
var oWrap = document.getElementById('wrap');
var aImg = oWrap.getElementsByTagName('img');
var aBtn = oWrap.getElementsByTagName('span');
var oPrev = document.getElementById('prev');
var oNext = document.getElementById('next');
var iNow =0;
function tab(){
for (var i =0;i<aBtn.length;i++){//清空所有按钮选中样式以及图片显示样式
aBtn[i].className='';
aImg[i].className='';
}
aBtn[iNow].className='active';//设置当前按钮选中样式以及当前图片透明度
aImg[iNow].className='on';
}
setInterval( function () {//每两秒循环变换下一张图片
iNow++;
if (iNow==aBtn.length)iNow=0;
tab();
},2000);
for (var i =0;i<aBtn.length;i++){
aBtn[i].index=i;//为按钮添加自定义属性（索引）目的是使图片和按钮相对应
//按钮
aBtn[i].οnmοuseοver= function () {
iNow=this.index; //是按钮所控制显示的图片与左右箭头控制显示的图片相对应
tab();
}
//下一个箭头
oNext.onclick = function () {
iNow++;
if (iNow==aImg.length)iNow=0;
tab();
}
//上一个箭头
oPrev.onclick = function () {
iNow--;
if (iNow==-1)iNow=aImg.length-1;
tab();
}
}
}