JavaScript模拟下拉菜单代码

优点：点击body区域同样可以隐藏下拉菜单，且不会和body已有的onclick事件冲突。
缺点：请大家指出，虚心接受！
运行框代码看似繁多，实属无奈，请下载附件，以便更好观察或修改~！

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>下拉菜单</title> <style type="text/css"> body{margin:20px auto;font-family:Arial, Helvetica, sans-serif;font-size:12px;width:950px;height:400px;border:solid 1px #aaa; position:relative;padding:10px;} ul{margin:0;padding:0;list-style:none;} .dropDownList{position:absolute;left:100px;top:100px;} /* .dropDownList div.dropdown select{display:none;}*/ .dropDownList div.dropdown{float:left;margin-right:50px;width:200px;} .dropDownList span{display:block;width:146px;height:26px;background:url(http://3.bp.blogspot.com/_bdBPvgEipxw/SRMUkLCdX0I/AAAAAAAAAP8/HgDXLapwpAw/s320/select.gif) left top no-repeat;line-height:26px;text-indent:12px;border:solid 1px #83BBD9;cursor:default;} .dropDownList span.over{background-position:left bottom;border-color:#B4C91A;}     .dropDownList ul{background:#eee;width:200px;display:none;}         .dropDownList ul li{height:20px;width:100%;padding:3px 0;text-indent:12px;cursor:default;}         .dropDownList ul li.over{background:#ccc;}     .dropDownList ul.show{display:block;} </style> </head> <body> <h1>JavaScript模拟下拉菜单，做的仓促，虚心接受批评。</h1> <form action="#" method="get"> <div class="dropDownList">     <div id="dropDownList1" class="dropdown">         <select name="birthday">             <option>请选择</option>             <option>1988</option>             <option>1989</option>         </select>         <span>请选择年份</span>         <ul></ul>     </div>     <div id="dropDownList2" class="dropdown">         <select name="sex">             <option>性别</option>             <option>男</option>             <option>女</option>         </select>         <span>请选择性别</span>         <ul></ul>     </div>     <div id="dropDownList3" class="dropdown">         <select name="student">             <option>幼儿班</option>             <option>小学</option>             <option>初中</option>         </select>         <span>请选择学历</span>         <ul></ul>     </div> </div> </form> </body> </html> <script type="text/javascript"> // JavaScript Document var ____configArray; function __initDropDownList(configArray){     //获取Select菜单     ____configArray=configArray;     var existArray=configArray.split("|");     for(var i=0;i<existArray.length;i++){         if(existArray[i].length<1){return;}         //根据参数分别获取div，并分别添加事件         var parentContainer=document.getElementById(existArray[i]);         if(!parentContainer){return;}         //获取下面的select，且获取其中的option         var selectObj=parentContainer.getElementsByTagName("select");         if(selectObj.length<1){return;}         var optionArray=selectObj[0].getElementsByTagName("option");         //获取option，并分别添加到各个li         var optionLength=optionArray.length;         for(var j=0;j<optionLength;j++){             //获取ul，以便能够添加项目             var ulObj=parentContainer.getElementsByTagName("ul");             if(ulObj.length<1){return;}             //获取span，以便能显示当前选择的项目             var spanObj=parentContainer.getElementsByTagName("span");             if(spanObj.length<1){return;}             var liObj=document.createElement("li");             var textNode=document.createTextNode(optionArray[j].firstChild.nodeValue)             liObj.appendChild(textNode);             liObj.setAttribute("currentIndex",j);             //给每个liObj添加事件             liObj.onclick=function(){                 selectCurrentItem(this.parentNode,this);             }             liObj.onmouseover=function(){this.className="over";}             liObj.onmouseout=function(){this.className="";}             ulObj[0].appendChild(liObj);             spanObj[0].onclick=function(event){                 //如果当前是显示的，就隐藏，反之亦然                 showHiddenUl(this);             }             spanObj[0].onmouseover=function(){this.className='over';}             spanObj[0].onmouseout=function(){this.className="";};             ulObj[0].onclick=function(){this.className="";}         }         parentContainer.onclick=function(event){             if(!event){event=window.event;}                 //阻止事件冒泡                 event.cancelBubble=true;                 var eventUlObj=this.getElementsByTagName("ul")[0];                 bodyClickHiddenUl(eventUlObj);         }     } } function selectCurrentItem(ulObj,currentObj){     var parentObj=ulObj.parentNode;     var spanObj=parentObj.getElementsByTagName("span")[0];     spanObj.firstChild.nodeValue=currentObj.firstChild.nodeValue;     var selectObj=parentObj.getElementsByTagName("select")[0];     selectObj.selectedIndex=parseInt(currentObj.getAttribute("currentIndex")); } function showHiddenUl(currentObj){     var parentNode=currentObj.parentNode;     var ulObj=parentNode.getElementsByTagName("ul")[0];     if(ulObj.className==""){         ulObj.className="show";     }else{         ulObj.className="";     } } //点击body区域（非"下拉菜单"）隐藏菜单 function addBodyClick(func) {     var bodyObj=document.getElementsByTagName("body")[0];     var oldBodyClick = bodyObj.onclick;         if (typeof bodyObj.onclick != 'function') {             bodyObj.onclick = func;         } else {             bodyObj.onclick = function() {             oldBodyClick();             func();         }     } } //隐藏所有的UL function bodyClickHiddenUl(eventUlObj){     var existArray=____configArray.split("|");     for(var i=0;i<existArray.length;i++){         if(existArray[i].length<1){return;}         //寻找所有UL并且隐藏         var parentContainer=document.getElementById(existArray[i]);         if(!parentContainer){return;}         var ulObj=parentContainer.getElementsByTagName("ul");         if(eventUlObj!=ulObj[0]){             ulObj[0].className="";         }     } } var __dropDownList="dropDownList1|dropDownList2|dropDownList3"; __initDropDownList(__dropDownList); //添加这个可以确保点击body区域的时候 也可以隐藏菜单 addBodyClick(bodyClickHiddenUl); </script>

[Ctrl+A 全选注:引入外部Js需再刷新一下页面才能执行]

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JavaScript模拟下拉菜单代码

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