js原生实现楼层效果

news2024/12/23 5:22:21

html文件

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        body .box {
            width: 1200px;
        }

        body .box {
            margin: 0 auto;
        }

        ul {
            list-style: none;
        }

        body .box ul li {
            height: 800px;
            background-color: silver;
            margin-bottom: 20px;
            font-size: 30px;
            font-weight: bold;
        }

        body .left {
            position: fixed;
            left: 20px;
            bottom: 100px;
            width: 100px;
            height: 250px;
            top: 50%;
            margin-top: -125px;
            background-color: silver;
        }

        body .left ul li {
            height: 50px;
            line-height: 50px;
            text-align: center;
            cursor: pointer;
        }

        body .current {
            color: #fff;
            background-color: tomato;
        }
    </style>

</head>

<body>
    <div id="box" class="box">
        <ul class="list">
            <li class="content-part" data-n="栏目一">栏目一</li>
            <li class="content-part" data-n="栏目二">栏目二</li>
            <li class="content-part" data-n="栏目三">栏目三</li>
            <li class="content-part" data-n="栏目四">栏目四</li>
            <li class="content-part" data-n="栏目五">栏目五</li>
        </ul>
    </div>
    <div class="left">
        <ul id="left-list">
            <li data-n="栏目一">栏目一</li>
            <li data-n="栏目二">栏目二</li>
            <li data-n="栏目三">栏目三</li>
            <li data-n="栏目四">栏目四</li>
            <li data-n="栏目五">栏目五</li>
        </ul>
    </div>

</body>
<script>
    var oList = document.getElementById('left-list');
    // 点击事件委托
    oList.onclick = function (e) {
        if (e.target.tagName.toLowerCase() == 'li') {
            // 取data-n值
            var n = e.target.getAttribute('data-n');
            // []属性选择器
            var contentPart = document.querySelector('.content-part[data-n=' + n + ']');
            // 设置卷动
            document.documentElement.scrollTop = contentPart.offsetTop;
        }
    }
    // 页面卷动时，左侧盒子栏目背景随之变化
var contents = document.querySelectorAll('.content-part');
var lis = document.querySelectorAll('#left-list li');
var offsetTopArr = [];
for (var i = 0; i < contents.length; i++) {
    offsetTopArr.push(contents[i].offsetTop);
}
// 为了方便比较，追加无穷大
offsetTopArr.push(Infinity);
// 监听卷动
var nowFloor = -1;
window.onscroll = function (e) {
    var nowScrollTop = document.documentElement.scrollTop;
    // break的i值即为盒子数组下标
    for (var i = 0; i < offsetTopArr.length; i++) {
        if (nowScrollTop >= offsetTopArr[i] && nowScrollTop < offsetTopArr[i + 1]) {
            break;
        }
    }
    // 楼层不等，进行样式更改
    if (nowFloor != i) {
        nowFloor = i;
        for (var j = 0; j < lis.length; j++) {
            if (j == i) {
                // 当前楼层添加样式
                lis[j].className = 'current';
            } else {
                // 去掉其他楼层的样式
                lis[j].className = '';
            }
        }
    }
}


</script>

</html>

实现效果