<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../move.js"></script>
<style>
.banner{width:1000px;height:300px;margin: 20px auto;position: relative;overflow: hidden}
.imgbox{position: absolute;left:0;
height: 300px;}
.imgbox img{width: 1000px;height:300px;float:left;}
.btns input{position: absolute;top:130px;width:40px;height:40px;border: none;background: rgba(200,200,200,0.5);}
#left{left:0}
#right{right:0}
</style>
</head>
<body>
<div class="banner">
<div class="imgbox">
<img src="img/1.jpg" alt="">
<img src="img/2.jpg" alt="">
<img src="img/3.jpg" alt="">
<img src="img/4.jpg" alt="">
<img src="img/5.jpg" alt="">
<!-- W1.复制第一张图片在最后，做过渡用 -->
<img src="img/1.jpg" alt="">
</div>
<div class="btns">
<input type="button" id="left" value="<<<">
<input type="button" id="right" value=">>>">
</div>
</div>
</body>
<script>
function Banner() {
this.left=document.querySelector("#left")
this.right=document.querySelector("#right")
this.imgs=document.querySelectorAll(".imgbox img");
this.imgbox=document.querySelector(".imgbox")
this.imgbox.style.width = this.imgs.length * this.imgs[0].offsetWidth + "px";
this.index=0;
this.init()
}
Banner.prototype.init=function () {
var that = this;
this.right.onclick = function () {
that.changeIndex1();
}
this.left.onclick = function () {
that.changeIndex2();
};
}
Banner.prototype.changeIndex1=function () {
if(this.index===this.imgs.length-1){
// W2.当索引到最后一个时，回到真正的第二张图片，索引为1
this.index=1;
// W3.索引设置好之后，将imgbox的left设置成初始值left:0
// move会从left:0走到-index1*width1000
this.imgbox.style.left=0
}
else {
this.index++;
}
this.display();
};
Banner.prototype.changeIndex2=function () {
if(this.index==0){
//当所引到第一个时，回到倒数第二张图片，索引位length-2
this.index=this.imgs.length-2;
//索引设置好之后，将left的初始值设为-5000px（也就是最后一张图所显示的left值）。
//move会从-5000走到-index*1000
this.imgbox.style.left=-(this.imgs.length-1)*this.imgs[0].offsetWidth+"px"
// console.log(-(this.imgs.length-1)*this.imgs[0].offsetWidth)
}
else{
this.index--
}
this.display()
};
Banner.prototype.display=function () {
move(this.imgbox,{
left:-this.imgs[0].offsetWidth*(this.index)
})
};
new Banner()
</script>
</html>简化版
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
.banner{width:1000px;height:300px;margin: 20px auto;position: relative;overflow: hidden;}
.imgbox{position: absolute;left:0;}
.imgbox img{width: 1000px;height:300px;float:left;}
.btns input{position: absolute;top:130px;width:40px;height:40px;border: none;background: rgba(200,200,200,0.5);}
#left{left:0}
#right{right:0}
</style>
</head>
<body>
<div class="banner">
<div class="imgbox">
<img src="img/1.jpg" alt="">
<img src="img/2.jpg" alt="">
<img src="img/3.jpg" alt="">
<img src="img/4.jpg" alt="">
<img src="img/5.jpg" alt="">
<!-- W1.复制第一张图片在最后，做过渡用 -->
<img src="img/1.jpg" alt="">
</div>
<div class="btns">
<input type="button" id="left" value="<<<">
<input type="button" id="right" value=">>>">
</div>
</div>
</body>
<script src="../move.js"></script>
<script>
// OOA:
// OOD:
// OOP:
function Banner(){
this.left = document.getElementById("left")
this.right = document.getElementById("right")
this.imgbox = document.querySelector(".imgbox")
this.img = this.imgbox.children;
this.imgbox.style.width = this.img.length * this.img[0].offsetWidth + "px";
this.index = 0;
this.init()
}
Banner.prototype.init = function(){
var that = this;
this.left.onclick = function(){
that.changeIndex(1)
}
this.right.onclick = function(){
that.changeIndex(-1)
}
}
Banner.prototype.changeIndex = function(type){
if(type == 1){
if(this.index == 0){
this.index = this.img.length-2;
this.imgbox.style.left = -(this.img.length-1) * this.img[0].offsetWidth + "px";
}else{
this.index--;
}
}else{
if(this.index == this.img.length-1){
// W2.当索引到最后一个时，回到真正的第二张图片，索引为1
this.index = 1;
// W3.索引设置好之后，将imgbox的left设置成初始值left:0
// move会从left:0走到-index1*width1000
this.imgbox.style.left = 0;
}else{
this.index++
}
}
this.display();
}
Banner.prototype.display = function(){
move(this.imgbox,{
left:-this.index * this.img[0].offsetWidth
})
}
new Banner();
</script>
</html>
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