jquery 树形折叠菜单

<style type="text/css">
    *{ padding:0; margin:0; border:0;}
    ul,li{ list-style:none;}
    body{ width:1000px; margin:6px auto; font-size:13px; line-height:18px;}
    #typebox{width:300px; border:1px solid #000; line-height:0;}
    #typebox .treeNode{ display:block;}
    #typebox .treeNode img{vertical-align:middle; border:0;}
    #typebox .treeNode a{padding: 0px 3px 0px 3px; text-decoration:none; cursor:auto; color:#666;}
    #typebox .dTree{ display:none;}
    #typebox .dTree.db{ display:block;}
    #typebox .dTree img{ vertical-align:middle; border:0;}
    #typebox .dTree a{padding: 0px 2px 0px 2px; text-decoration:none; cursor:auto; color:#666;}
    #typebox .dTree a:hover{ text-decoration:underline;}
    
</style>

<script type="text/javascript">
    $(function(){
        $(".treeNode").click(function(){
            //$(this).children("img").attr("src", "img/minus.gif");
            
            $(this).next().toggleClass("db");//将当前点击的树的子菜单显示
            $(this).children("img").attr("src", ($(this).next().is(":hidden") ? "img/plus.gif" : "img/minus.gif"));//当子菜单隐藏时，树的“——”号变成“+”号，当子菜单显示时，加号变成减号
            
            //$(this).next().is(":hidden") ? "img/plus.gif" : "img/minus.gif")用来判断子菜单是否隐藏，如果隐藏，就将图片改成加号，如果显示，把图片改成减号
            
            /*if($(this).next().is(":hidden"))
            {
                alert("hidden");
            }
            else {
                alert("show");
            }*/
        });
    });
</script>

<div id="typebox">
    <div class="treeNode">
        <img src="img/plus.gif" alt="" /><a href="#" title="">核心</a>
    </div>
    <ul class="dTree">
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="http://www.baidu.com" target="_blank" title="">each</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">size</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">length</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/joinbottom.gif" /><a href="#" title="">selector</a></li>
    </ul>
    <div class="treeNode">
        <img src="img/plus.gif" alt="" /><a href="#" title="">属性</a>
    </div>
    <ul class="dTree">
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">each</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">size</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">length</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/joinbottom.gif" /><a href="#" title="">selector</a></li>
    </ul>
    <div class="treeNode">
        <img src="img/plus.gif" alt="" /><a href="#" title="">选择器</a>
    </div>
    <ul class="dTree">
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">each</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">size</a></li>
        <li><img src="img/line.gif" alt="" /><img src="img/join.gif" /><a href="#" title="">length</a></li>
        <li><img src="img/joinbottom.gif" alt="" /><img src="img/joinbottom.gif" /><a href="#" title="">selector</a></li>
    </ul>
</div>

 参考图片：empty.gif(是一张空白的图片)        join.gif     joinbottom.gif      line.gif      minus.gif       plus.gif