动态添加选择区

<script type="text/javascript">
            if (window.ActiveXObject && !window.XMLHttpRequest){
                window.XMLHttpRequest=function(){
                    return new ActiveXObject((navigator.userAgent.toLowerCase().indexOf('msie 6') != -1) ? 'Microsoft.XMLHTTP' : 'Msxml2.XMLHTTP');
                };
            }//取得XMLHttpRequest对象     
            var req;
            var flagSelect;
            var hereClasses = new Array(3);
            
            function testName(flag,obj)//使用Ajax访问服务器
      		{
      			 var value = obj.value;
	             flagSelect = flag; //标记一下当前是选择省,还是选择市
	             if(flagSelect == "1"){
	             	//hereClasses[0] = obj.options[obj.selectedIndex].text;
	             	//document.getElementById("hereClassDiv").innerHTML = hereClasses[0];
	             }
	             if(flagSelect == "2"){
	             	//hereClasses[1] = obj.options[obj.selectedIndex].text;
	             	//document.getElementById("hereClassDiv").innerHTML = hereClasses[0] + " > " + hereClasses[1];
	             }
	             if(flagSelect == "3"){
	             	//hereClasses[2] = obj.options[obj.selectedIndex].text;
	             	//document.getElementById("hereClassDiv").innerHTML = hereClasses[0] + " > " + hereClasses[1] + " > " + hereClasses[2];
	             	return;
	             }
	             req=new XMLHttpRequest();
	             if (req) 
	             {
	                 req.onreadystatechange=setValue;
	             }
	             req.open('POST',"hereClassSelect.do?method=selectHereClass&flag="+flag+"&value="+value);//把参数带到服务器中
	             req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	             req.send(null);
	         }
            function setValue()
            {
                if (req.readyState==4 )//访问到服务器
                {           
                    if(req.status==200)//正确返回
                    {    
                        if(flagSelect=="1")//如果选择某个省要更新市和区
                        {
                            var v=req.responseText;//req.responseText是服务器返回来的字符串
                            paint(document.getElementById("hereSecondClass"),v); //更新市下拉框
                            paint(document.getElementById("hereThirdClass"),"");  //清空区下拉框
                            
                        }
                        if(flagSelect=="2")//如果选择某市,只需改变区
                        {
                            var v=req.responseText;
                            paint(document.all("hereThirdClass"),v); //更新区下拉框
                        }
                    }
                }
            }
            function paint(obj,value)//根据一对数据去更新一个下拉框
            {
                 var v=value.split(";");   //得到一些数据,(修改过了..)
                 obj.options.length=0;   //先清空原来的数据
                    
                 for(var i=0;i<v.length-1;i++)//把新得到的数据显示上去
                 {
                     var option = new Option(v[i].split(",")[1], v[i].split(",")[0]);
                     obj.add(option);
                 }
            }   
        </script>


	<select id="hereFirstClass" name="hereFirstClass" style="width:130"
									size="8" onchange="testName(1,this);">
									<c:forEach items="${hereFirstClasses}" var="hereFirstClass" >
										<option value="${hereFirstClass.id }">${hereFirstClass.classNameZh }</option>
									</c:forEach>
									
								</select>

								<select id="hereSecondClass" name="hereSecondClass" style="width:130"
									size="8" onchange="testName(2,this);">
								</select>

								<select id="hereThirdClass" name="hereSecondClass" style="width:130"
									size="8" onchange="testName(3,this);">
								</select>
								<div class="add_Delete"><input type="button" value="↓填加" onclick="addline()"/>
      <input type="button" value="x 删除" onclick="delline()"/></div>
      <script type="text/javascript" >
      	function addline() {
      		var num = document.getElementById("select1");
      		if(num.length>5) {
      			alert("最多只能添加6行");
      			return false;
      		}
      		var obj;
      		obj = document.createElement("option");
      		
      		var obj1 = document.getElementById("hereFirstClass");
      		var obj2 = document.getElementById("hereSecondClass");
      		var obj3 = document.getElementById("hereThirdClass");
      		if(document.getElementById("hereFirstClass").value=="") {
      			alert("请选择主营行业");
      			return false;
      		}
      		var hereFirstValue = document.getElementById("hereFirstClass").value;
			var hereFirstName = document.getElementById("hereFirstClass").options[obj1.selectedIndex].text;
      		
      		if(document.getElementById("hereSecondClass").value=="") {
      			obj.value = hereFirstValue;
      			obj.text = hereFirstName;
      			document.getElementById("select1").add(obj);
      		}else if(document.getElementById("hereThirdClass").value=="") {
      			var hereSecondValue = document.getElementById("hereSecondClass").value;
      			var hereSecondName = document.getElementById("hereSecondClass").options[obj2.selectedIndex].text;
      			obj.value = hereFirstValue+"//"+hereSecondValue;
      			obj.text = hereFirstName+"//"+hereSecondName;
      			document.getElementById("select1").add(obj);
      		}else{
      			var hereThirdValue = document.getElementById("hereThirdClass").value;
      			var hereThirdName = document.getElementById("hereThirdClass").options[obj3.selectedIndex].text;
      			var hereSecondValue = document.getElementById("hereSecondClass").value;
      			var hereSecondName = document.getElementById("hereSecondClass").options[obj2.selectedIndex].text;
      			obj.value = hereFirstValue+"//"+hereSecondValue+"//"+hereThirdValue;
      			obj.text = hereFirstName+"//"+hereSecondName+"//"+hereThirdName;
      			document.getElementById("select1").add(obj);
      		}
      		
      	}
      	
      	function delline() {
      		document.all.select1.options.remove(document.all.select1.selectedIndex);
      		document.all.select1.selectIndex=0;
      	}
      
      </script>