原生js轮播图实现

 <!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
* {
padding: 0;
margin: 0;
list-style: none;
border: 0;
} .all {
width: 500px;
height: 200px;
padding: 7px;
border: 1px solid #ccc;
margin: 100px auto;
position: relative;
} .screen {
width: 500px;
height: 200px;
overflow: hidden;
position: relative;
} .screen li {
width: 500px;
height: 200px;
overflow: hidden;
float: left;
} .screen ul {
position: absolute;
left: 0;
top: 0px;
width: 3000px;
} .all ol {
position: absolute;
right: 10px;
bottom: 10px;
line-height: 20px;
text-align: center;
} .all ol li {
float: left;
width: 20px;
height: 20px;
background: #fff;
border: 1px solid #ccc;
margin-left: 10px;
cursor: pointer;
} .all ol li.current {
background: yellow;
} #arr {
display: none;
} #arr span {
width: 40px;
height: 40px;
position: absolute;
left: 5px;
top: 50%;
margin-top: -20px;
background: #000;
cursor: pointer;
line-height: 40px;
text-align: center;
font-weight: bold;
font-family: '黑体';
font-size: 30px;
color: #fff;
opacity: 0.3;
border: 1px solid #fff;
} #arr #right {
right: 5px;
left: auto;
}
</style>
</head>
<body>
<div class="all" id='all'>
<div class="screen" id="screen">
<ul id="ul">
<li><img src="data:images/carousel/1.jpg" width="500" height="200" /></li>
<li><img src="data:images/carousel/2.jpg" width="500" height="200" /></li>
<li><img src="data:images/carousel/3.jpg" width="500" height="200" /></li>
<li><img src="data:images/carousel/4.jpg" width="500" height="200" /></li>
<li><img src="data:images/carousel/5.jpg" width="500" height="200" /></li>
</ul>
<ol>
</ol>
<div id="arr">
<span id="left"><</span>
<span id="right">></span>
</div>
</div>
</div> <script>
//1.获取事件源
var all = document.getElementById("all");
var screen = all.firstElementChild || all.firstChild;
var imgWidth = screen.offsetWidth;
var ul = screen.firstElementChild || screen.firstChild;
var ol = screen.children[1];
var div = screen.lastElementChild || screen.lastChild;
var spanArr = div.children; //2.复制第一张图片所在的li,添加到ul的最后面
var ulNewLi = ul.children[0].cloneNode(true);
ul.appendChild(ulNewLi); //3.给ol添加li,ul的个数-1个,并点亮第一个按钮
for (var i = 0; i < ul.children.length - 1; i++) {
var olNewLi = document.createElement("li");
olNewLi.innerHTML = i + 1;
ol.appendChild(olNewLi);
} var olLiArr = ol.children;
olLiArr[0].className = "current"; //4.鼠标放到ol的li上,切换图片
for (var i = 0; i < olLiArr.length; i++) {
olLiArr[i].index = i;
olLiArr[i].onmouseover = function(){
for (var j = 0; j < olLiArr.length; j++) {
olLiArr[j].className = "";
}
this.className = "current";
//鼠标放到小的方块上的时候索引值和key以及square同步
key = square = this.index;
//移动盒子
animate(ul,-this.index * imgWidth);
}
} //5.添加定时器
var timer = setInterval(autoPlay,1000);
//固定向右切换图片,两个定时器(一个记录图片,一个记录小方块)
var key = 0;
var square = 0; function autoPlay(){
//通过控制key的自增来模拟图片的索引值,然后移动ul
key ++;
if (key > olLiArr.length) {
//图片已经滑动到最后一张,接下来,跳转到第一张,然后在滑动到第二张
ul.style.left = 0;
key = 1;
}
animate(ul,-key * imgWidth);
//通过控制square的自增来模拟小方块的索引值,然后点亮盒子
square ++;
if (square > olLiArr.length - 1) {
square = 0;
}
for (var i = 0; i < olLiArr.length; i++) {
olLiArr[i].className = "";
}
olLiArr[square].className = "current";
} //鼠标放上去清除定时器,移开后再开启定时器
all.onmouseover = function(){
div.style.display = "block";
clearInterval(timer);
}
all.onmouseout = function(){
div.style.display = "none";
timer = setInterval(autoPlay, 1000);
} //6.左右切换图片,鼠标放上去显示,移开隐藏
spanArr[0].onclick = function(){
//通过控制key的自增来模拟图片的索引值,然后移动ul
key --;
if (key < 0) {
//先移动到最后一张,然后key的值取之前一张的索引值,然后在向前移动
ul.style.left = -imgWidth * (olLiArr.length) + "px";
key = olLiArr.length - 1;
}
animate(ul, -key * imgWidth); //通过控制square的自增来模拟小方块的索引值,然后点亮盒子
//排他思想做小方块
square--;
if (square < 0) { //索引值不能大于等于5,如果等于5,立刻变为0;
square = olLiArr.length - 1;
}
for (var i = 0; i < olLiArr.length; i++) {
olLiArr[i].className = "";
}
olLiArr[square].className = "current";
}
spanArr[1].onclick = function() {
//右侧的和定时器一模一样
autoPlay();
}
function animate(ele, target) {
clearInterval(ele.timer);
var speed = target > ele.offsetLeft ? 10 : -10;
ele.timer = setInterval(function() {
var val = target - ele.offsetLeft;
ele.style.left = ele.offsetLeft + speed + "px";
if (Math.abs(val) < Math.abs(speed)) {
ele.style.left = target + "px";
clearInterval(ele.timer);
}
}, 10)
} //7.
</script>
</body>
</html>
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