老师请检查，是否有待优化

来源：6-3 编写跑马灯轮播图特效

张小阳_

2022-07-14 10:01:39

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>carousel</title>
    <style>
        * {
            padding: 0;
            margin: 0;
            text-decoration: none;
            list-style: none;
        }

        .carousel {
            width: 650px;
            height: 360px;
            margin: 0 auto;
            position: relative;
            overflow: hidden;
        }

        .carousel ul {
            width: 4000px;
            position: relative;
            left: 0;
            transition: left ease .5s;
        }

        .carousel ul li {
            float: left;
        }

        .carousel a {
            width: 50px;
            height: 50px;
            background-color: rgba(0, 0, 0, .3);
            border-radius: 50%;
            position: absolute;
            top: 50%;
            margin-top: -25px;
            text-align: center;
            line-height: 50px;
            font-size: 25px;
        }

        .carousel .leftBtn {
            left: 10px;
        }

        .carousel .rightBtn {
            right: 10px;
        }
    </style>
</head>

<body>
    <div class="carousel">
        <ul id="list">
            <li><img src="./images/0.jpg" alt=""></li>
            <li><img src="./images/1.jpg" alt=""></li>
            <li><img src="./images/2.jpg" alt=""></li>
            <li><img src="./images/3.jpg" alt=""></li>
            <li><img src="./images/4.jpg" alt=""></li>
        </ul>
        <a id="leftBtn" class="leftBtn" href="javascript:;">&lt;</a>
        <a id="rightBtn" class="rightBtn" href="javascript:;">&gt;</a>
    </div>

    <script>
        var rightBtn = document.getElementById('rightBtn');
        var list = document.getElementById('list');
        // 克隆假图
        var cloneImg = list.firstElementChild.cloneNode(true);
        list.appendChild(cloneImg);
        //  节流锁
        var lock = true;
        // 定义一个图片个数,从0开始计
        var idx = 0;
        rightBtn.onclick = function () {
            if (!lock) return;
            list.style.transition = 'left ease .5s';
            idx++;
            if (idx > 4) {
                setTimeout(function () {
                    idx = 0;
                    list.style.left = -idx * 650 + 'px';
                    list.style.transition = 'none';     //去掉过渡动画
                }, 500);
            }
            list.style.left = -idx * 650 + 'px';
            lock = false;
            setTimeout(function () {
                lock = true;
            }, 500);
        };

        // 绑定左键
        var leftBtn = document.getElementById('leftBtn');
        leftBtn.onclick = function () {
            if (!lock) return;
            if (idx <= 0) {
                idx = 5;
                list.style.left = -idx * 650 + 'px';
                list.style.transition = 'none';
                setTimeout(function () {
                    list.style.transition = 'left ease .5s';
                    idx = 4;
                    list.style.left = -idx * 650 + 'px';
                }, 0);
            } else {
                idx--;
                list.style.left = -idx * 650 + 'px';
            }
            lock = false;
            setTimeout(function () {
                lock = true;
            }, 500);
        };
    </script>
</body>

</html>

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