How to do multiple onchange events in one view

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I have a dropdown for Country, State, and City. Country to State Javascript onchange works fine. Now I want to populate the cities dropdown. I created another onchange event but it is not working and I am thinking it is not working because the dropdown is repopulated by the JavaScript. The original dropdown before populated is a @Html.DropdownListFor this is replaced by an Html options select by JavaScript. My question is how do I rearrange the JavaScript code so that I can add the cities dropdown. Below is the JavaScript code and View of the 3 items in the View.

Thanks for your help!

What I have tried:

View:

C#

<div class="form-group">
    @Html.LabelFor(model => model.Country, htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
        @Html.DropDownListFor(model => Model.Country, Model.Countries, "---Select Country---", new { @class = "form-control", @id = "ddlCountry" })
        @Html.ValidationMessageFor(model => model.Country, "", new { @class = "text-danger" })
    </div>
</div>

<div class="form-group">
    @Html.LabelFor(model => model.State, htmlAttributes: new { @class = "control-label col-md-2" })
    <div id="State" class="col-md-10">
        @Html.DropDownListFor(model => model.State, new List<SelectListItem>(),"---Select State---", new { @class = "form-control", @id = "ddlState" })
        @Html.ValidationMessageFor(model => model.State, "", new { @class = "text-danger" })
    </div>
</div>

<div class="form-group">
    @Html.LabelFor(model => model.City, htmlAttributes: new { @class = "control-label col-md-2" })
    <div id="City" class="col-md-10">
        @Html.DropDownListFor(model => model.City, new List<SelectListItem>(), "---Select City---", new { @class = "form-control"})
        @Html.ValidationMessageFor(model => model.City, "", new { @class = "text-danger" })
    </div>
</div>

JavaScript:

JavaScript

<script type="text/javascript">
    $(function () {
        $('#ddlCountry').change(function () {
            $.ajax({
                type: "post",
                url: "/Addresses/GetStates",
                data: { countryId: $('#ddlCountry').val() },
                datatype: "json",
                traditional: true,
                success: function (data) {
                    var st = "<select class='form-control' id='ddlState'>";
                    st = st + '<option value="">--Select State--</option>';
                    for (var i = 0; i < data.length; i++) {
                        st = st + '<option value=' + data[i].Value + '>' + data[i].Text + '</option>';
                    }
                    st = st + '</select>';
                    $('#State').html(st);
                }
            });
        });
    });

    $(function () {
        $('#ddlState').change(function () {
            $.ajax({
                type: "post",
                url: "/Addresses/GetCities",
                data: { stateId: $('#ddlState').val() },
                datatype: "json",
                traditional: true,
                success: function (data) {
                    var ct = "<select  class='form-control' id='ddlCity'>";
                    ct = ct + '<option value="">--Select City--</option>';
                    for (var i = 0; i < data.length; i++) {
                        ct = ct + '<option value=' + data[i].Value + '>' + data[i].Text + '</option>';
                    }
                    ct = ct + '</select>';
                    $('#City').html(ct);
                }
            });
        });
    });
</script>

Posted 3-Nov-18 15:00pm

Member 13812021

Updated 6-Nov-18 4:17am

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Richard Deeming · Answer 1 · 2018-11-06T04:17:00

You wire up an event handler for a specific element. You then completely replace that element, which means the new element doesn't have any event handlers.

You could solve the problem by using delegated events[^]. But there's a simpler solution.

Rather than replacing the entire <select> element, just replace the options within it:

JavaScript

$(function(){
    $('#ddlCountry').change(function(){
        $.ajax({
            type: "post",
            url: "/Addresses/GetStates",
            data: { countryId: $(this).val() },
            datatype: "json",
            traditional: true
        }).then(function(data){
            var list = $("#ddlState");
            var stateId = list.val();
            
            list.empty();
            
            $.each(data, function(index, item){
                var opt = $("<option/>").attr("value", item.Value).text(item.Text);
                list.append(opt);
            });
            
            list.val(stateId);
        });
    });
    
    $('#ddlState').change(function(){
        $.ajax({
            type: "post",
            url: "/Addresses/GetCities",
            data: { stateId: $(this).val() },
            datatype: "json",
            traditional: true
        }).then(function(data){
            var list = $("#ddlCity");
            var cityId = list.val();
            
            list.empty();
            
            $.each(data, function(index, item){
                var opt = $("<option/>").attr("value", item.Value).text(item.Text);
                list.append(opt);
            });
            
            list.val(cityId);
        });
    });
});