JS 新浪下拉菜单

2023-10-09 12:09:58

思考：首先在CSS布局上就出错了，导致后面设置JS时就有很大的问题

<!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>Document</title>
    <style>
        .nav {
            background-color: rgb(235, 225, 225);
            line-height: 30px;
            height: 30px;
            position: relative;
        }
        
        ul {
            margin: 0px 0px;
            padding: 0 0 0 0;
        }
        
        .nav1 li,
        .nav2 li,
        .nav3 li {
            display: block;
            padding-left: 10px;
            height: 20px;
            padding-top: 5px;
            padding-bottom: 5px;
            border: 1px solid orange;
            margin-top: -1px;
        }
        
        .nav1,
        .nav2,
        .nav3 {
            display: none
        }
        
        .nav1 {
            background-color: white;
            width: 80px;
            position: absolute;
            top: 0px;
            left: 0px
        }
        
        .nav2 {
            background-color: white;
            width: 100px;
            position: absolute;
            top: 0px;
            left: 80px
        }
        
        .nav3 {
            background-color: white;
            width: 120px;
            position: absolute;
            top: 0px;
            left: 160px
        }
        
        .nav div {
            width: 80px;
            text-align: center;
            line-height: 30px;
            float: left
        }
        
        .tort {
            position: relative;
            left: 0px
        }
        
        .se {
            background-color: rgb(201, 192, 192);
            color: orange
        }
        
        ul li:hover {
            background-color: orange;
        }
    </style>
</head>

<body>
    <div class="nav">
        <div>微博</div>
        <div>博客</div>
        <div>邮箱</div>
    </div>
    <div class="tort">
        <div class="nav1">
            <ul>
                <li>私信</li>
                <li>评论</li>
                <li>@我</li>
            </ul>
        </div>
        <div class="nav2">
            <ul>
                <li>博客评论</li>
                <li>未读提醒</li>
            </ul>
        </div>
        <div class="nav3">
            <ul>
                <li>免费邮箱</li>
                <li>VIP邮箱</li>
                <li>企业邮箱</li>
                <li>新浪客户邮箱</li>
            </ul>
        </div>
    </div>
    <script>
        //获得导航栏元素
        var nav = document.querySelector('.nav')
            //注册下拉事件点击的时候，对应的下拉菜单就是显示的（一一对应）因此需要索引号
            //给na.children即下面的所有li设置自定义属性
            //用不着，因为下面下拉菜单都进行了分别命名，但这样就不能用循环了
        nav.children[0].setAttribute('data-index', '0')
        nav.children[1].setAttribute('data-index', '1')
        nav.children[2].setAttribute('data-index', '2')
        var nav1 = document.querySelector('.nav1')
        var nav2 = document.querySelector('.nav2')
        var nav3 = document.querySelector('.nav3')
            //获取下拉菜单子元素
            //应该用data-index来获取
            // var tort = document.querySelector('.tort')
            // nav1.setAttribute('data-idn', '0')
            // nav2.setAttribute('data-idn', '1')
            // nav3.setAttribute('data-idn', '2')

        // var nn = 
        // console.log(nn)
        //添加事件
        for (var i = 0; i < nav.children.length; i++) {
            nav.children[i].onmouseover = function() {
                this.className = 'se'
            }
            nav.children[i].onmouseout = function() {
                    this.className = ''
                }
                //添加下拉菜单显示属性

        }
        // nav.children[0].onmouseover = function() {
        //     nav1.style.display = 'block'
        //     nav2.style.display = ''
        //     nav3.style.display = ''
        // }
        // nav.children[1].onmouseover = function() {
        //     nav2.style.display = 'block'
        //     nav1.style.display = ''
        //     nav3.style.display = ''
        // }
        // nav.children[2].onmouseover = function() {
        //     nav3.style.display = 'block'
        //     nav2.style.display = ''
        //     nav1.style.display = ''
        // }
    </script>

</body>

</html>

下拉菜单的基本布局

导航栏里面的li都要有鼠标经过的效果，所以需要循环注册事件

<!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>Document</title>
    <style>
        .nav li {
            list-style: none;
        }
        
        .nav>li>a:hover {
            background-color: #eee;
        }
        
        .nav ul {
            display: block;
            position: absolute;
            top: 41px;
            left: 0px;
            width: 100%;
            border-left: 1px solid #fecc5b;
            border-right: 1px solid #fecc5b
        }
        
        .nav ul li {
            border-bottom: 1px solid #fecc5b;
        }
        
        .nav ul li a:hover {
            background-color: #fff5da;
        }
        
        .m1 {
            position: absolute;
            top: 0px;
            left: 0px;
        }
        
        .m1 {
            position: absolute;
            top: 0px;
            left: 20px;
        }
    </style>
</head>

<body>
    <ul class="nav">
        <li>
            <a href="#">微博</a>
            <ul class="m1">
                <li><a href="">私信</a>
                </li>
                <li><a href="">评论</a></li>
                <li><a href="">@我</a></li>

            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul>
                <li><a href="">私信</a>
                </li>
                <li><a href="">评论</a></li>
                <li><a href="">@我</a></li>
            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul class="m1">
                <li><a href="">私信</a>
                </li>
                <li><a href="">评论</a></li>
                <li><a href="">@我</a></li>
            </ul>
        </li>
        <li>
            <a href="#">微博</a>
            <ul>
                <li><a href="">私信</a>
                </li>
                <li><a href="">评论</a></li>
                <li><a href="">@我</a></li>
            </ul>
        </li>
    </ul>
    <script>
        //获取元素
        var nav = document.querySelector('.nav')
        var lis = nav.children
            //循环注册事件
        for (var i = 0; i < lis.length; i++) {
            lis[i].onmouseover = function() {
                this.children[1].style.display = 'block'

            }
            lis[i].onmouseout = function() {
                this.children[1].style.display = ''

            }
        }
    </script>
</body>

</html>

未完成

注意用节点的方式获取元素

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