如何在javascript onchange应用asp.net时以编程方式更改下拉列表中的选定项
我在codebehind上有两个下拉列表和一个隐藏字段,每个都是通过attribute.add添加javascript onchange事件的代码,还有一个按钮来执行一些动态操作,比如在运行时添加控件 当我点击该按钮时,下拉列表被重置。为了保持状态,我有一个带有下拉菜单的隐藏字段,我从隐藏字段中获取selectedvalue,但通过编码DDCity.Items.FindByValue似乎不起作用,有人能帮忙吗如何在javascript onchange应用asp.net时以编程方式更改下拉列表中的选定项,javascript,asp.net,drop-down-menu,onchange,selectedvalue,Javascript,Asp.net,Drop Down Menu,Onchange,Selectedvalue,我在codebehind上有两个下拉列表和一个隐藏字段,每个都是通过attribute.add添加javascript onchange事件的代码,还有一个按钮来执行一些动态操作,比如在运行时添加控件 当我点击该按钮时,下拉列表被重置。为了保持状态,我有一个带有下拉菜单的隐藏字段,我从隐藏字段中获取selectedvalue,但通过编码DDCity.Items.FindByValue似乎不起作用,有人能帮忙吗 protected void Page_Load(object sender, E
protected void Page_Load(object sender, EventArgs e)
{ DDCountry.Attributes.Add("onChange", "javascript:BufferAddDDCountry('" + DDCountry.ClientID + "');");
DDCity.Attributes.Add("onChange", "javascript:BufferAddDDCity('" + DDCity.ClientID + "');");}
if (hiddenDDCityValue.Text != "0")
{
DDCity.Items.FindByValue(hiddenDDCityValue.Text).Selected = true;// this dont work
}
if (!IsPostBack)
{ this.populateCountry();populateCity();}
javascript代码
<script type="text/javascript">
function BufferAddDDCountry(objDd) {
try {
var objHidden = document.getElementById('hiddenDDcountryValue');
objHidden.value = document.getElementById(objDd).value;
} catch (e) {
alert(e);
}
};
function BufferAddDDCity(objDd) {
try {
var objHidden = document.getElementById('hiddenDDCityValue');
objHidden.value = document.getElementById(objDd).value;
} catch (e) {
alert(e);
}
};
</script>
function setSelectedValue(dropdownList, selectedValue) {
var dropdown = document.getElementById(dropdownList);
for (var i = 0; i < dropdown.options.length; i++) {
if (dropdown.options[i].value == selectedValue) {
dropdown.options[i].value = selectedValue;
dropdown.options[i].selected = true;
break;
}
}
return;
}
功能BufferAddDDCountry(objDd){
试一试{
var objHidden=document.getElementById('hiddendCountryValue');
objHidden.value=document.getElementById(objDd).value;
}捕获(e){
警报(e);
}
};
函数BufferAddDDCity(objDd){
试一试{
var objHidden=document.getElementById('hiddendCityValue');
objHidden.value=document.getElementById(objDd).value;
}捕获(e){
警报(e);
}
};
我终于让它在javascript中工作了,希望这能帮助其他人这里是代码
代码隐藏页面加载
ScriptManager.RegisterStartupScript(UpdatePanel, this.GetType(), "Dropdownselectedvaluechange", "javascript:setSelectedValue('" + DDCity.ClientID + "','" + hiddenDDCityValue.Text + "');", true);
javascript代码
<script type="text/javascript">
function BufferAddDDCountry(objDd) {
try {
var objHidden = document.getElementById('hiddenDDcountryValue');
objHidden.value = document.getElementById(objDd).value;
} catch (e) {
alert(e);
}
};
function BufferAddDDCity(objDd) {
try {
var objHidden = document.getElementById('hiddenDDCityValue');
objHidden.value = document.getElementById(objDd).value;
} catch (e) {
alert(e);
}
};
</script>
function setSelectedValue(dropdownList, selectedValue) {
var dropdown = document.getElementById(dropdownList);
for (var i = 0; i < dropdown.options.length; i++) {
if (dropdown.options[i].value == selectedValue) {
dropdown.options[i].value = selectedValue;
dropdown.options[i].selected = true;
break;
}
}
return;
}
功能设置selectedValue(下拉列表,selectedValue){
var dropdown=document.getElementById(dropdownList);
对于(变量i=0;i