Get Latitude and Longitude using JavaScript based on user input in ASP.Net

Hi EmadKhan,

Refer the below code. Instead of making ajax call use the below simple method.

<div align="center">
    <table>
        <tr>
            <td>
                Unit/Street:
            </td>
            <td>
                <asp:TextBox ID="txtUnit" class="change" runat="server" Width="250px" Text="1" />
            </td>
        </tr>
        <tr>
            <td>
                Street Name:
            </td>
            <td>
                <asp:TextBox ID="txtStreet" class="change" runat="server" Width="250px" Text="Gandroo" />
            </td>
        </tr>
        <tr>
            <td>
                City/Suburb:
            </td>
            <td>
                <asp:TextBox ID="txtCity" class="change" runat="server" Width="250px" Text="Gungahlin" />
            </td>
        </tr>
        <tr>
            <td>
                State:
            </td>
            <td>
                <asp:TextBox ID="txtState" runat="server" Width="250px" Text="ACT" />
            </td>
        </tr>
        <tr>
            <td>
                Post Code:
            </td>
            <td>
                <asp:TextBox ID="txtPostalCode" runat="server" Width="250px" Text="2912" />
            </td>
        </tr>
        <tr>
            <td>
                Country:
            </td>
            <td>
                <asp:DropDownList runat="server" ID="ddlCountry">
                    <asp:ListItem Text="Select" />
                    <asp:ListItem Text="Australia" />
                    <asp:ListItem Text="India" />
                </asp:DropDownList>
            </td>
        </tr>
        <tr>
            <td>
                Latitude:
            </td>
            <td>
                <asp:TextBox ID="txtLatitude" runat="server" Width="250px" />
            </td>
        </tr>
        <tr>
            <td>
                Longitude:
            </td>
            <td>
                <asp:TextBox ID="txtLongitude" runat="server" Width="250px" />
            </td>
        </tr>
    </table>
</div>
<div>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?sensor=false&key=YourGoogleApiKey"></script>
    <script type="text/javascript">
        $(function () {
            $('#ddlCountry').on("change", function () {
                var unit = $('#txtUnit').val();
                var street = $('#txtStreet').val();
                var city = $('#txtCity').val();
                var state = $('#txtState').val();
                var postal = $('#txtPostalCode').val();
                var country = $(this).find("option:selected").text();
                if (unit !== '' && street != '' && city != '' && state != '' && postal != '' && country != '') {
                    var address = unit + ',' + street + ',' + city + ',' + state + ',' + postal + ',' + country;
                    var geocoder = new google.maps.Geocoder();
                    geocoder.geocode({ 'address': address }, function (results, status) {
                        if (status == google.maps.GeocoderStatus.OK) {
                            var latitude = results[0].geometry.location.lat();
                            var longitude = results[0].geometry.location.lng();
                            $('#txtLatitude').val(latitude);
                            $('#txtLongitude').val(longitude);
                        } else {
                            alert("Request failed.")
                        }
                    });
                }
            });
        });
    </script>
</div>