如何在客户端更快地显示DropDownList数据加载？

Question

I am using C# ASP.NET 3.5 in my application. In my application, I do have a page where a DropDownList is populated based on another DropDownList select value.

Each of my DropDownList has an selectedIndexChange method on its selection. Due to this data retrieval is slower.

Is there any client side AJAX tools to handle this to make it faster? Please advise.

I have attached an image of my page.

Answer 1

Yeah.There is an ajax control named CascadingDropDown

  <cc1:CascadingDropDown ID="cdlportfolio" TargetControlID="ddlportfolio" 
                                        PromptValue="" ServicePath="ServiceVB.asmx" ServiceMethod="Getportfolio" runat="server" 
                                        Category="portfolio" LoadingText = "Loading..." />

Answer 2

$(function() {
$('#<%=ddlstate.ClientID %>').attr('disabled', 'disabled');
$('#<%=ddlcity.ClientID %>').attr('disabled', 'disabled');
$('#<%=ddlstate.ClientID %>').append('<option selected="selected" value="0">Select State</option>');
$('#<%=ddlcity.ClientID %>').empty().append('<option selected="selected" value="0">Select Region</option>');
$('#<%=ddlcountries.ClientID %>').change(function() {
var country = $('#<%=ddlcountries.ClientID%>').val()
$('#<%=ddlstate.ClientID %>').removeAttr("disabled");
$('#<%=ddlcity.ClientID %>').empty().append('<option selected="selected" value="0">Select Region</option>');
$('#<%=ddlcity.ClientID %>').attr('disabled', 'disabled');
$.ajax({
type: "POST",
url: "jQueryCascadingDropdownExample.aspx/BindStates",
data: "{'country':'" + country + "'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
var j = jQuery.parseJSON(msg.d);
var options;
for (var i = 0; i < j.length; i++) {
options += '<option value="' + j[i].optionValue + '">' + j[i].optionDisplay + '</option>'
}
$('#<%=ddlstate.ClientID %>').html(options)
},
error: function(data) {
alert('Something Went Wrong')
}
});
});

Please refer the below link.

http://www.aspdotnet-suresh.com/2013/10/jquery-cascading-dropdown-list-in-aspnet.html