jQuery实现轮播图效果

<div class="slider">
 <ul>
 <li><a href="#" ><img src="images/1.jpg" alt=""></a></li>
 <li><a href="#" ><img src="images/2.jpg" alt=""></a></li>
 <li><a href="#" ><img src="images/3.jpg" alt=""></a></li>
 <li><a href="#" ><img src="images/4.jpg" alt=""></a></li>
 <li><a href="#" ><img src="images/5.jpg" alt=""></a></li>
 </ul>
 
 <div class="arrow">
 <span class="left">&lt;</span>
 <span class="right">&gt;</span>
 </div>

 <div class="box">
 <ul>
 <li class="show"></li>
 <li></li>
 <li></li>
 <li></li>
 <li></li>
 </ul>
 </div>
</div>

* {
margin: 0;
padding: 0;
list-style: none;
}

.slider {
width: 790px;
height: 340px;
margin: 100px auto;
position: relative;
}

.slider>ul>li {
display: none;
position: absolute;
}

.slider li:first-child {
display: block;
}

.arrow {
display: none;
}

.slider:hover .arrow,
.slider:hover .box {
display: block;
}

.left,
.right {
width: 30px;
height: 60px;
font-size: 30px;
background-color: rgba(0, 0, 0, 0.1);
color: white;
position: absolute;
top: 50%;
margin-top: -30px;
line-height: 60px;
text-align: center;
cursor: pointer;
}

.left:hover,
.right:hover {
background-color: rgba(0, 0, 0, .5);
}

.left {
left: 0;
}

.right {
right: 0;
}

.box {
width: 150px;
height: 20px;
position: absolute;
left: 50%;
margin-left: -75px;
bottom: 20px;
display: none;
}

.box li {
width: 12px;
height: 12px;
background-color: white;
border-radius: 50%;
display: inline-block;
float: left;
margin-left: 12px;
}

.show{
background-color: orangered !important;
}

$(function() {
var num = 0;
$(".right").click(function() {
num++;
if (num === $(".slider>ul>li").length) {
num = 0;
}
$(".slider li").eq(num).fadeIn().siblings("li").fadeOut();
$(".box li").eq(num).addClass("show").siblings("li").removeClass("show");
});

$(".left").on("click", function() {
num--;
if (num === -1) {
num = $(".slider>ul>li").length - 1;
}
$(".slider li").eq(num).fadeIn().siblings("li").fadeOut();
$(".box li").eq(num).addClass("show").siblings("li").removeClass("show");
});

$(".box li").on("click", function() {
var idx = $(this).index();
$(".slider li").eq(idx).fadeIn().siblings("li").fadeOut();
$(".box li").eq(idx).addClass("show").siblings("li").removeClass("show");
});
});