jsavascript 面向对象的下拉菜单

<!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>

 

posted @ 2017-05-02 18:39  KSnow  阅读(244)  评论(0编辑  收藏  举报