select option generate value from ajax on change

Question

I have here the code and flow of my project i have 3 select here one for continent one for country one for city i get data to populate these select from ajax request it is now working fine i just want to make a bit fancy so i want to have a few function

1.When Continent is select the list of country for that continent is listed in the country list when the change happens I want the city to also show the cities of the first entry in the country currently it does not happened what i do is i still need to change the entry in country select to show the list of cities

2.Question is do i need to add another ajax request inside the ajax request for continent i am not sure this one is feasible i tried it, it is not working for now

Ajax Code

$('.continentname').change(function() {
        var id = $(this).find(':selected')[0].id;
        //alert(id); 
        $.ajax({
            type:'POST',
            url:'../include/continent.php',
            data:{'id':id},
            success:function(data){
                // the next thing you want to do 
    var country= document.getElementById('country');
              $(country).empty();
    var city = document.getElementById('city');
              $(city).empty();
    for (var i = 0; i < data.length; i++) {
    $(country).append('<option id=' + data[i].sysid + ' value=' + data[i].name + '>' + data[i].name + '</option>');
    }
            }
        });

    });

$('.countryname').change(function() {
        var id = $(this).find(':selected')[0].id;
        $.ajax({
            type:'POST',
            url:'../include/country.php',
            data:{'id':id},
            success:function(data){
                // the next thing you want to do 
    var city = document.getElementById('city');
              $(city).empty();
    for (var i = 0; i < data.length; i++) {
    $(city).append('<option id=' + data[i].sysid + ' value=' + data[i].name + '>' + data[i].name + '</option>');
    }
            }
        });

    });

From database i put the value into the option select like

$("#continent").val(continentid);
$("#continent").change();
$("#country").change();
$("#country").val(countryid);
$("#city").val(cityid);

Answer 1

You can trigger a change event for the country element once it is populated

$('.continentname').change(function () {
    var id = $(this).find(':selected')[0].id;
    //alert(id); 
    $.ajax({
        type: 'POST',
        url: '../include/continent.php',
        data: {
            'id': id
        },
        success: function (data) {
            // the next thing you want to do 
            var $country = $('#country');
            $country.empty();
            $('#city').empty();
            for (var i = 0; i < data.length; i++) {
                $country.append('<option id=' + data[i].sysid + ' value=' + data[i].name + '>' + data[i].name + '</option>');
            }

            //manually trigger a change event for the contry so that the change handler will get triggered
            $country.change();
        }
    });

});

$('.countryname').change(function () {
    var id = $(this).find(':selected')[0].id;
    $.ajax({
        type: 'POST',
        url: '../include/country.php',
        data: {
            'id': id
        },
        success: function (data) {
            // the next thing you want to do 
            var $city = $('#city');
            $city.empty();
            for (var i = 0; i < data.length; i++) {
                $city.append('<option id=' + data[i].sysid + ' value=' + data[i].name + '>' + data[i].name + '</option>');
            }
        }
    });
});