1、效果如下图：
2、源码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>JavaScript banner轮播 左右切换 圆点点击切换</title> <style type="text/css">
div,ul,li,a,span,img{margin:0;padding:0;}
#banner {
overflow:hidden;
width:100%;
height:400px;
position:relative;
float:left;
padding-bottom: 10px;
}
#tab>img:not(:first-child){
display:none;
}
.lunbo_btn {
height: 15px;
width: 100%;
margin: 0px auto;
margin-top: -40px;
position: absolute;
z-index: 3;
text-align: center;
}
.lunbo_btn span {
width:14px;
height:14px;
display:inline-block;
background-color:#b4b5b7;
border-radius:50%;
margin:0px 2px;
cursor:pointer;
}
.lunbo_btn span.hover {
background-color:#ffb23c;
}
.arrow {
display: none;
width: 30px;
height: 60px;
background-color: rgba(0,0,0,0.4);
position: absolute;
top: 50%;
margin-top: -30px;
z-index:999;
}
.arrow span {
display: block;
width: 10px;
height: 10px;
border-bottom: 2px solid #fff;
border-left: 2px solid #fff;
}
.slider_left {
margin: 25px 0 0 10px;
transform: rotate(45deg);
}
.prve {
left: 0;
}
.next {
right: 0;
}
.slider_right {
margin: 25px 0 0 5px;
transform: rotate(-135deg);
}
.arrow:hover{background:#444;}
#banner:hover .arrow{display:block;}
</style> </head>
<body> <div id="banner">
<!-- 轮播图片 -->
<div id="tab">
<img class="tabImg" src="data:images/banner1.jpg" height="400"/>
<img class="tabImg" src="data:images/banner2.jpg" height="400"/>
<img class="tabImg" src="data:images/banner3.jpg" height="400"/>
<img class="tabImg" src="data:images/banner4.jpg" height="400"/>
</div>
<!-- 指示符 -->
<div class="lunbo_btn">
<span num="0" class="tabBtn hover"></span>
<span num="1" class="tabBtn"></span>
<span num="2" class="tabBtn"></span>
<span num="3" class="tabBtn"></span>
</div>
<!-- 左右切换按钮 -->
<div class="arrow prve">
<span class="slider_left"></span>
</div>
<div class="arrow next">
<span class="slider_right"></span>
</div>
</div> <script type="text/javascript"> //轮播图
var curIndex=0;//初始化
var img_number = document.getElementsByClassName('tabImg').length;
var _timer = setInterval(runFn,2000);//2秒
function runFn(){ //运行定时器
curIndex = ++curIndex == img_number ? 0 : curIndex;//算法 4为banner图片数量
slideTo(curIndex);
} //圆点点击切换轮播图
window.onload = function () { //为按钮初始化onclick事件
var tbs = document.getElementsByClassName("tabBtn");
for(var i=0;i<tbs.length;i++){
tbs[i].onclick = function () {
clearInterval(_timer);//细节处理，关闭定时，防止点切图和定时器函数冲突
slideTo(this.attributes['num'].value);
curIndex = this.attributes['num'].value
_timer = setInterval(runFn,2000);//点击事件处理完成，继续开启定时轮播
}
}
} var prve = document.getElementsByClassName("prve");
prve[0].onclick = function () {//上一张
clearInterval(_timer);//细节处理，关闭定时，防止点切图和定时器函数冲突
curIndex--;
if(curIndex == -1){
curIndex = img_number-1;
}
slideTo(curIndex);
_timer = setInterval(runFn,2000);//点击事件处理完成，继续开启定时轮播
} var next = document.getElementsByClassName("next");
next[0].onclick = function () {//下一张
clearInterval(_timer);//细节处理，关闭定时，防止点切图和定时器函数冲突
curIndex++;
if(curIndex == img_number){
curIndex =0;
}
slideTo(curIndex);
_timer = setInterval(runFn,2000);//点击事件处理完成，继续开启定时轮播
} //切换banner图片 和 按钮样式
function slideTo(index){
console.log(index)
var index = parseInt(index);//转int类型
var images = document.getElementsByClassName('tabImg');
for(var i=0;i<images.length;i++){//遍历每个图片
if( i == index ){
images[i].style.display = 'inline';//显示
}else{
images[i].style.display = 'none';//隐藏
}
}
var tabBtn = document.getElementsByClassName('tabBtn');
for(var j=0;j<tabBtn.length;j++){//遍历每个按钮
if( j == index ){
tabBtn[j].classList.add("hover"); //添加轮播按钮hover样式
curIndex=j;
}else{
tabBtn[j].classList.remove("hover");//去除轮播按钮hover样式
}
} } </script>
</body>
</html>
完毕！
good job! good luck!