js 面向对象的 下拉菜单
<script>
// 获取对象 遍历对象操作 显示模块 隐藏模块
function List(id) { // 获取对象
this.id = document.getElementById(id); // 取 id 值
this.lis = this.id.children[0].children; // 获取一级菜单所有的li
}
// init 初始化
List.prototype.init = function () { // 遍历所有的li 显示和隐藏
var that = this;
for (var i = 0; i < this.lis.length; i++) {
this.lis[i].index = i;
this.lis[i].onmouseover = function () {
that.show(this.children[0]); // 显示出来
}
this.lis[i].onmouseout = function () {
that.hide(this.children[0]); // 隐藏起来
}
}
}
// 显示模块
List.prototype.show = function (obj) {
obj.style.display = "block";
}
// 隐藏模块
List.prototype.hide = function (obj) {
obj.style.display = "none";
}
var list = new List("list"); // 实例化了一个对象 叫 list
list.init();
</script>整体代码如下：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style type="text/css">
* {
padding: 0;
margin: 0;
list-style: none;
}
.all {
width: 330px;
height: 30px;
background: url(img/bg.jpg) no-repeat;
margin: 100px auto;
line-height: 30px;
text-align: center;
padding-left: 10px;
margin-bottom: 0;
}
.all ul li {
width: 100px;
height: 30px;
background: url(img/libg.jpg);
float: left;
margin-right: 10px;
position: relative;
cursor: pointer;
}
.all ul ul {
position: absolute;
left: 0;
top: 30px;
display: none;
}
</style>
</head>
<body>
<div class="all" id="list">
<ul>
<li>一级菜单
<ul>
<li>二级菜单</li>
<li>二级菜单</li>
<li>二级菜单</li>
</ul>
</li>
<li>一级菜单
<ul>
<li>二级菜单</li>
<li>二级菜单</li>
<li>二级菜单</li>
</ul>
</li>
<li>一级菜单
<ul>
<li>二级菜单</li>
<li>二级菜单</li>
<li>二级菜单</li>
</ul>
</li>
</ul>
</div>
</body>
</html>
<script>
// 获取对象 遍历对象操作 显示模块 隐藏模块
function List(id) { // 获取对象
this.id = document.getElementById(id); // 取 id 值
this.lis = this.id.children[0].children; // 获取一级菜单所有的li
}
// init 初始化
List.prototype.init = function () { // 遍历所有的li 显示和隐藏
var that = this;
for (var i = 0; i < this.lis.length; i++) {
this.lis[i].index = i;
this.lis[i].onmouseover = function () {
that.show(this.children[0]); // 显示出来
}
this.lis[i].onmouseout = function () {
that.hide(this.children[0]); // 隐藏起来
}
}
}
// 显示模块
List.prototype.show = function (obj) {
obj.style.display = "block";
}
// 隐藏模块
List.prototype.hide = function (obj) {
obj.style.display = "none";
}
var list = new List("list"); // 实例化了一个对象 叫 list
list.init();
</script>