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js无级树形菜单二例

阅读：4003 输入：2014-05-31 14:56:58

//该菜单支持无限级数,增加级数方法:三级时level赋值5,以后每增加一级level值增2
//该例CSS样式表已经定义到5级样式,
//套用该函数只需在树状菜单根节点上使用id="side_menu",列表需使用UL
/*==========================================================*/
var level = 5;
var n = level;
//判断该对象是否包含于side_menu中
function isInSideMenu(obj){
if(n){ n--;
if(obj.getAttribute&&obj.getAttribute("id")=="side_menu"){n = level;return true;}
if(obj.nodeType==9){n = level;return false;}//超过当前文档树结构时返回false
else{return isInSideMenu(obj.parentNode);}
}
n = level;
return false;
}
//菜单折叠效果函数
function foldMenu(){
    if(this.nextSibling&&this.nextSibling.nextSibling){
    if(this.nextSibling.nextSibling.style.display=="block"){
    this.nextSibling.nextSibling.style.display ="none";
    this.innerHTML = this.innerHTML.replace("-","+");
    }else{
    this.nextSibling.nextSibling.style.display ="block";
    this.innerHTML = this.innerHTML.replace("+","-");
    }
    }else{
    this.innerHTML = this.innerHTML.replace("+","-");
    }
}
//初始化树状菜单
function intSideMenu(){
var as = document.getElementsByTagName("a");
var uls = document.getElementsByTagName("ul");
var sidemenuUL = document.getElementById("side_menu");
for(var i=0;i<as.length;i++){
if(isInSideMenu(as[i])){
as[i].onclick= foldMenu;
as[i].innerHTML = as[i].innerHTML.replace("-","+");
}
}//给所有树状菜单内的a绑定foldMenu函数
for(var j=0;j<uls.length;j++){
if(isInSideMenu(uls[j]))uls[j].style.display ="none";//初始化隐藏树状菜单
}
sidemenuUL.style.display = "block";//显示根菜单
}
intSideMenu();
/*====================//树状菜单结束==========================*/
</script>

</html>
<!DOCTYPE html>
<html>
<head>
<style>
#tree {
    width: 150px;
}
#tree, #tree ul {
    list-style: none; margin: 0; padding: 0; padding: 10px;
}
#tree li {
    border: 1px solid #00f; padding: 10px; cursor: pointer;
}
#tree ul {
    display: none;
}
</style>
<script>
window.onload = function() {
    var tree = document.getElementById("tree");
    var lis = tree.getElementsByTagName("li");
    for(var i = 0; i < lis.length; i++) {
        (function(a) {
            lis[a].onclick = function() {
                if(typeof this.getElementsByTagName("ul") !== null) {
                    var ul_first = this.getElementsByTagName("ul")[0];
                    if(ul_first.style.display == "block")
                        ul_first.style.display = "none";
                    else
                        ul_first.style.display = "block";
                }
            };
        })(i);
    }
};
</script>
</head>
<body>
<ul id="tree">
<li>菜单一
<ul>
<li>1-1</li><li>1-2</li><li>1-3</li><li>1-4</li>
</ul>
</li>
<li>菜单二
<ul>
<li>2-1</li><li>2-2</li><li>2-3</li><li>2-4</li>
</ul>
</li>
<li>菜单三
<ul>
<li>3-1</li><li>3-2</li><li>3-3</li><li>3-4</li>
</ul>
</li>
</ul>
</body>
</html>

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