js实现滚动定位

直接上代码

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

<head>
    <meta charset="UTF-8">
    <title>爱淘气购物网－JQuery网页定位导航特效</title>
    <style>
    /*All tag*/

    html,
    body,
    div,
    ul,
    li,
    img,
    h1,
    h2 {
        margin: 0;
        padding: 0;
    }

    ul {
        list-style: none;
    }

    a {
        text-decoration: none;
        color: #333;
    }
    /*menu*/

    #menu {
        position: fixed;
        top: 100px;
        left: 50%;
        margin-left: 400px;
    }

    #menu>li>a {
        display: block;
        padding: 10px 15px;
        height: 30px;
        line-height: 30px;
        font-size: 14px;
        font-weight: bold;
        margin: 5px 0;
    }

    #menu>li>a:hover,
    #menu>li>a.current {
        color: #fff;
        background-color: #0088bb;
    }
    /*content*/

    #content {
         800px;
        margin: 30px auto;
    }

    h1 {
        color: #0088bb;
        font-size: 30px;
        margin-bottom: 10px;
    }

    .item {
        border: 1px dotted #0088bb;
        padding: 20px;
        margin-bottom: 20px;
    }

    .item>h2 {
        font-size: 16px;
        padding-bottom: 5px;
        border-bottom: 2px solid #0088bb;
        margin-bottom: 10px;
    }

    .item-list>li {
        display: inline-block;
        margin-right: 10px;
    }

    .item-list>li>a>img {
         230px;
        height: 230px;
        border: none;
    }
    /* IE6 hack*/

    * html,
    * html body {
        background-image: url(about:blank);
        background-attachment: fixed;
    }

    * html #menu {
        /*position: fixed*/
        position: absolute;
        top: expression((e=document.documentElement.scrollTop ? e: document.body.scrollTop) + 100 + 'px');
    }
    </style>
</head>

<body>
    <ul id="menu">
        <li><a class="current" href="#item1">1F&nbsp;男装</a></li>
        <li><a href="#item2">2F&nbsp;女装</a></li>
        <li><a href="#item3">3F&nbsp;美妆</a></li>
        <li><a href="#item4">4F&nbsp;数码</a></li>
        <li><a href="#item5">5F&nbsp;母婴</a></li>
    </ul>
    <div id="content">
        <h1>爱淘气购物网</h1>
        <div id="item1" class="item">
            <h2>1F&nbsp;男装</h2>
            <ul class="item-list">
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p1.qhimgs4.com/dmfd/160_90_/t01a8d3c891c7c3e202.jpg?size=640x400" alt="商品图片"></a>
                </li>
            </ul>
        </div>
        <div id="item2" class="item">
            <h2>2F&nbsp;女装</h2>
            <ul class="item-list">
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p2.qhimgs4.com/dmfd/160_90_/t01c5e14034226e1d97.jpg?size=640x400" alt="商品图片"></a>
                </li>
            </ul>
        </div>
        <div id="item3" class="item">
            <h2>3F&nbsp;美妆</h2>
            <ul class="item-list">
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t017b1f5993c08af904.jpg?size=640x400" alt="商品图片"></a>
                </li>
            </ul>
        </div>
        <div id="item4" class="item">
            <h2>4F&nbsp;数码</h2>
            <ul class="item-list">
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p0.qhimgs4.com/dmfd/160_90_/t014922d8477716f299.jpg?size=640x400" alt="商品图片"></a>
                </li>
            </ul>
        </div>
        <div id="item5" class="item">
            <h2>5F&nbsp;母婴</h2>
            <ul class="item-list">
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
                <li>
                    <a href="#"><img src="http://p4.qhimg.com/dmfd/160_90_/t0100eb94d000a1b3c9.jpg" alt="商品图片"></a>
                </li>
            </ul>
        </div>
        <div style=" 100%;height: 1000px;"></div>
    </div>
    <script src="http://libs.baidu.com/jquery/1.10.2/jquery.min.js"></script>
   
    <script>
    //定义getByClassName函数，让函数实现根据className获取对象并返回
    function getByClassName(obj, cls) {
        var elements = obj.getElementsByTagName("*");
        var result = [];
        for (var i = 0; i < elements.length; i++) {
            if (elements[i].className == cls) {
                result.push(elements[i]);
            }
        }
        return result;
    }

    //定义hasClass函数，确认对象是否包含对应的class
    function hasClass(obj, cls) {
        return obj.className.match(new RegExp("(\s|^)" + cls + "(\s|$)"));
    }

    //定义removeClass函数，让函数实现删除对象的class 
    function removeClass(obj, cls) {
        if (hasClass(obj, cls)) {
            //remove
            var reg = new RegExp("(\s|^)" + cls + "(\s|$)");
            obj.className = obj.className.replace(reg, "");
        }
    }

    //定义addClass函数，让函数实现给对象增加class 
    function addClass(obj, cls) {
        if (!hasClass(obj, cls)) {
            obj.className += " " + cls;
        }
    }

    //页面加载完毕执行以下函数
    window.onload = function() {
        //页面滚动时，执行以下函数
        window.onscroll = function() {
            var top = document.documentElement.scrollTop || document.body.scrollTop;

            var menus = document.getElementById("menu").getElementsByTagName("a");

            var items = getByClassName(document.getElementById("content"), "item");

            var currentId = "";

            for (var i = 0; i < items.length; i++) {
                var _item = items[i];
                var _itemTop = _item.offsetTop;
                if (top > _itemTop) {
                    currentId = _item.id;
                } else {
                    break;
                }
            }

            //给正确的menu下的a元素class赋值current
            if (currentId) {
                for (var j = 0; j < menus.length; j++) {
                    var _menu = menus[j];
                    var _href = _menu.href.split("#");
                    if (_href[_href.length - 1] != currentId) {
                        removeClass(_menu, "current");
                    } else {
                        addClass(_menu, "current");
                    }
                }
            }
        }
    }
    </script>
</body>

</html>
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原文地址：https://www.cnblogs.com/chenmiaosong/p/8413134.html