<body>
<ul>
<li id="top">微博</li>
<li class="hide">私信</li>
<li class="hide">评论</li>
<li class="hide">@我</li>
</ul>
</body>
<script>
// 大概方法：
// 1.获取元素
var nav = document.querySelector(".nav");
var lis = nav.children; //得到4个li
// 循环注册事件
for (let 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 = "none";
};
}
</script>
<script>
var top = document.getElementById("top");
var hide = document.getElementsByClassName("hide"); //返回的是一个元素集合
var ul = document.querySelector("ul");
// console.log('123');
ul.onmouseover = function () {
//使用top.onmouseover时会在鼠标一离开zd元素时，下拉菜单立即隐藏，应该效果一样才对啊？
hide[0].style.display = "block";
hide[1].style.display = "block";
hide[2].style.display = "block";
};
ul.onmouseout = function () {
hide[0].style.display = "none";
hide[1].style.display = "none";
hide[2].style.display = "none";
};
</script>
