作业分析
下拉菜单 2025-03-23 220537.png
代码示例
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>下拉菜单</title>
<style>
/* 公共样式 */
*{
margin: 0;
padding: 0;
box-sizing: border-box;
}
html,body{
width: 100%;
height: 100%;
}
body{
font-size: 62.5%;
}
/* 自定义样式 */
.nav{
width: 100%;
height: 50px;
background-color: #bea594;
display: flex;
justify-content: center;
}
.page-header{
width: 1200px;
height: 100%;
background-color: #d7ad9b;
display: flex;
list-style: none;
}
.page-header > .item{
padding: 10px 50px;
font-size: 18px;
text-align: center;
cursor: pointer;
position: relative;
}
.page-header > .item:hover{
background-color: #e5dcd1;
color: #333;
font-weight: 500;
}
.children{
display: none;
position: absolute;
top: 50px;
left: 0;
list-style: none;
padding: 10px 20px;
background-color: #e6d7d7;
}
.children > li{
line-height: 50px;
}
.children > li{
background-color: #c4cdd0;
color: #333;
}
</style>
</head>
<body>
<div class="nav">
<ul class="page-header">
<li class="item">首页</li>
<li class="item">文章
<ul class="children">
<li>发表文章</li>
<li>我的文章</li>
<li>关注的文章</li>
<li>喜欢的文章</li>
</ul>
</li>
<li class="item">相册
<ul class="children">
<li>我的相册</li>
<li>上传照片</li>
</ul>
</li>
<li class="item">消息
<ul class="children">
<li>我的私信</li>
<li>我的留言</li>
</ul>
</li>
</ul>
</div>
<!-- JS代码写在网页的最后面 -->
<script>
//获取所有的一级菜单；<li class="item"></li>
let _lis = document.getElementsByClassName("item")
console.log(_lis)
//封装函数
function toggleMune(child,is_show){
//获取当前点击标签内部的<ul class="children"></ul>
let _children = child.getElementsByClassName("children")
//判断是否有子标签
if(_children.length > 0 ){
//如果有，获取子标签
let c = _children[0]
//判断显示子标签
c.style.display = is_show
}
}
//循环依次添加单击事件
for(let i = 0;i < _lis.length;i ++){
//console.log(_lis[i],"---")
//依次添加单击事件 -> 鼠标进入事件
_lis[i].onmouseenter = function(){
//显示子菜单
toggleMune(_lis[i],"block")
}
//依次添加一个鼠标离开事件
_lis[i].onmouseleave = function(){
//隐藏子菜单
toggleMune(_lis[i],"none")
}
}
</script>
</body>
</html>
