JavaScript轮播图

需求：
鼠标移动到下标页码时，也转换到相对应的图片；
多张图片可以自动轮播；
鼠标移动至图片时，停止自动轮播；
可以手动左右调节；
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>原生JS轮播图</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .outer{
            position: relative;
            top: 20px;
            cursor: pointer;
        }
        .outer .img-box .img-item {
            display: none;
            position: absolute;
            top: 0;
            left: 50%;
            transform: translateX(-50%);
        }
        .active{
            display: block !important;
        }
        .outer ul{
            position: absolute;
            top: 250px;
            left: 50%;
            transform: translateX(-50%);
            text-align: center;
        }
        .outer ul li.page-number{
            list-style-type: none;
            display: inline-block;
            color: black;
            margin: 0 6px;
            font-size: 12px;
            width: 20px;
            height: 20px;
            background-color: #05dfff;
            line-height: 20px;
            text-align: center;
            border-radius: 50%;
        }
        .page-active{
            background-color: #0000FF !important;
        }
        .outer .mover{
            position: absolute;
            top: 110px;
            left: 50%;
            height: 60px;
            width: 40px;
            background-color: rgba(255,255,255,0.65);
            line-height: 60px;
            text-align: center;
            font-size: 26px;
            display: none;
            user-select: none;  /*用户点击时，内容不能被选中*/
        }
        .outer .leftMover{
            margin-left: -260px;
        }
        .outer .rightMover{
            margin-left: 220px;
        }
    </style>
</head>
<body>
    <div id="outer" class="outer">
        <div class="img-box">
            <img src="../img/1.jpg" class="img-item active">
            <img src="../img/2.jpg" class="img-item">
            <img src="../img/3.jpg" class="img-item">
            <img src="../img/4.jpg" class="img-item">
        </div>
        <ul>
            <li class="page-number page-active">1</li>
            <li class="page-number">2</li>
            <li class="page-number">3</li>
            <li class="page-number">4</li>
        </ul>
        <a id="leftMover" class="mover leftMover">&lt;</a>
        <a id="rightMover" class="mover rightMover">&gt;</a>
    </div>
    <script>
        var objectImgItems = document.getElementsByClassName("img-item");
        var objectRowItems = document.getElementsByClassName("page-number");
        var objectOuter = document.getElementById("outer");
        var objectMover = document.getElementsByClassName("mover");
        var objectLeftMover = document.getElementById("leftMover");
        var objectRightMover =  document.getElementById("rightMover");
        <!-- 获取node在nodeList中的索引值 -->
        function getIndex(node, nodeList) {
            for (var index=0; index<nodeList.length; index++){
                if (nodeList[index] === node){
                    return index
                }
            }
        }
        <!-- 根据传入的页码索引值，转换图片和页码 -->
        function move(numberIndex) {
            for (var i=0; i<objectImgItems.length; i++){
                if (i === numberIndex) {
                    objectImgItems[i].classList.add("active");
                    objectRowItems[i].classList.add("page-active");
                } else {
                    objectImgItems[i].classList.remove("active");
                    objectRowItems[i].classList.remove("page-active");
                }
            }
        }
        <!-- 鼠标覆盖页码时，图片和页码进行转换 -->
        for (var i=0; i<objectRowItems.length; i++){
            objectRowItems[i].onmouseover = function () {
                var numberIndex = getIndex(this, objectRowItems);
                move(numberIndex);
                pageNumber = numberIndex;
            };
        }
        <!-- 鼠标移动到整个模块，则显示左右移动的图标，图片停止自动转换 -->
        objectOuter.onmouseover = function () {
            clearInterval(intervalId);
            for (var i=0; i<objectMover.length; i++){
                objectMover[i].classList.add("active");
            }
        };
        <!-- 鼠标离开整个模块，则隐藏左右移动的图标，图片开始自动转换 -->
        objectOuter.onmouseout = function () {
            intervalId = setInterval(directionMove, 2000);
            for (var i=0; i<objectMover.length; i++){
                objectMover[i].classList.remove("active");
            }
        };
        <!-- 添加页码变量，通过自增、自减，实现左右转换 -->
        var pageNumber = 0;
        function directionMove(isLeft) {
            if (isLeft){
                if (pageNumber === 0) {
                    pageNumber = 4;
                }
                pageNumber--;
            } else {
                if (pageNumber === 3) {
                    pageNumber = -1;
                }
                pageNumber++;
            }
            move(pageNumber);
        }
        <!-- 添加定时器，实现自动转换 -->
        var intervalId = setInterval(directionMove, 2000);
        <!-- 右转换 -->
        objectRightMover.onclick = function () {
            directionMove();
        };
        <!-- 左转换 -->
        objectLeftMover.onclick = function () {
            directionMove(true);
        }
    </script>
</body>
</html>
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