页面中有一个dropdownlist二级联动和js的二级联动,当autopostback=true时,点击dropdownlist后,下拉单city总是变为“请选择城市”请大家帮我看看,应该怎样解决这个问题。谢谢。js代码如下
<script language="JavaScript" type="text/javascript">
//定义了城市的二维数组,里面的顺序跟省份的顺序是相同的。通过selectedIndex获得省份的下标值来得到相应的城市数组
var city=[
["北京","天津","上海","重庆"],
["南京","苏州","南通","常州"],
["福州","福安","龙岩","南平"],
["广州","潮阳","潮州","澄海"],
["兰州","白银","定西","敦煌"]
];
function getCity(){
//获得省份下拉框的对象
var sltProvince=document.form1.province;
//获得城市下拉框的对象
var sltCity=document.form1.city;
//得到对应省份的城市数组
var provinceCity=city[sltProvince.selectedIndex - 1]; //清空城市下拉框,仅留提示选项
sltCity.length=1;
//将城市数组中的值填充到城市下拉框中
for(var i=0;i<provinceCity.length;i++){
sltCity[i+1]=new Option(provinceCity[i],provinceCity[i]);
}
}
</script>
<meta name="keywords" content="text/aspxl; charset=gb2312" http-equiv="Content-Type">
<LINK rel="stylesheet" type="text/css" href="../../css/style.css">
</HEAD>
<body>
html代码如下: <form id="form1" runat="server">
<asp:dropdownlist style="Z-INDEX: 0" id="dropCate" runat="server" ></asp:dropdownlist>
<asp:dropdownlist style="Z-INDEX: 0" id="dropCate1" runat="server"></asp:dropdownlist>
<SELECT NAME="province" onChange="getCity()" id="province" runat="server">
<OPTION VALUE="0" selected>请选择省份
</OPTION>
<OPTION VALUE="直辖市">直辖市
</OPTION>
<OPTION VALUE="江苏省">江苏省
</OPTION>
<OPTION VALUE="福建省">福建省
</OPTION>
<OPTION VALUE="广东省">广东省
</OPTION>
<OPTION VALUE="甘肃省">甘肃省
</OPTION>
</SELECT>
<SELECT NAME="city" id="city" runat="server" >
<OPTION VALUE="请选择城市" selected>请选择城市
</OPTION>
</SELECT>
<script language="JavaScript" type="text/javascript">
//定义了城市的二维数组,里面的顺序跟省份的顺序是相同的。通过selectedIndex获得省份的下标值来得到相应的城市数组
var city=[
["北京","天津","上海","重庆"],
["南京","苏州","南通","常州"],
["福州","福安","龙岩","南平"],
["广州","潮阳","潮州","澄海"],
["兰州","白银","定西","敦煌"]
];
function getCity(){
//获得省份下拉框的对象
var sltProvince=document.form1.province;
//获得城市下拉框的对象
var sltCity=document.form1.city;
//得到对应省份的城市数组
var provinceCity=city[sltProvince.selectedIndex - 1]; //清空城市下拉框,仅留提示选项
sltCity.length=1;
//将城市数组中的值填充到城市下拉框中
for(var i=0;i<provinceCity.length;i++){
sltCity[i+1]=new Option(provinceCity[i],provinceCity[i]);
}
}
</script>
<meta name="keywords" content="text/aspxl; charset=gb2312" http-equiv="Content-Type">
<LINK rel="stylesheet" type="text/css" href="../../css/style.css">
</HEAD>
<body>
html代码如下: <form id="form1" runat="server">
<asp:dropdownlist style="Z-INDEX: 0" id="dropCate" runat="server" ></asp:dropdownlist>
<asp:dropdownlist style="Z-INDEX: 0" id="dropCate1" runat="server"></asp:dropdownlist>
<SELECT NAME="province" onChange="getCity()" id="province" runat="server">
<OPTION VALUE="0" selected>请选择省份
</OPTION>
<OPTION VALUE="直辖市">直辖市
</OPTION>
<OPTION VALUE="江苏省">江苏省
</OPTION>
<OPTION VALUE="福建省">福建省
</OPTION>
<OPTION VALUE="广东省">广东省
</OPTION>
<OPTION VALUE="甘肃省">甘肃省
</OPTION>
</SELECT>
<SELECT NAME="city" id="city" runat="server" >
<OPTION VALUE="请选择城市" selected>请选择城市
</OPTION>
</SELECT>
点一下不就刷新了,刷新了可不就选在“请选择城市”上了。
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager> <asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
</ContentTemplate>
</asp:UpdatePanel>
<html>
<head>
<style>
#d1{
position:absolute;
width:450;
height:350;
background-Color:#cccccc;
left:60;
top:80;
}
#d2{
height:30;
background-Color:blue;
color:white;
font-size:20pt;
}
#d3{
padding-left:50;
padding-top:50;
font-size:15pt;
}
</style>
<script>
var arr1 = new Array();
arr1[0] = [new Option('--方向--','-1')];
arr1[1] = [new Option('计算机方向1','jsj1'),new Option('计算机方向2','jsj2'),new Option('计算机方向3','jsj3')];
arr1[2] = [new Option('英语方向1','eng1'),new Option('英语方向1','eng1')];
function change(index){
var s2Obj = document.getElementById('s2');
s2Obj.length = arr1[index].length;
for(i=0;i<arr1[index].length;i++){
s2Obj.options[i] = arr1[index][i];
}
}
</script>
</head>
<body>
<div id="d1">
<div id="d2">级联下拉列表</div>
<div id="d3">
<select id="s1" name="select1" style="width:150;" onchange="change(this.selectedIndex);">
<option value="-1">--专业--</option>
<option value="compute">计算机</option>
<option value="english">英语</option>
</select>
<select id="s2" name="select2" style="width:150;">
<option value="-1">--方向--</option>
</select>
</div>
</div>
</body>
</html>
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList Style="z-index: 0" ID="dropCate" runat="server" OnSelectedIndexChanged="dropCate_SelectedIndexChanged" AutoPostBack="True">
</asp:DropDownList>
<asp:DropDownList Style="z-index: 0" ID="dropCate1" runat="server">
</asp:DropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="dropCate" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>