How to populate dependable drop-down using Ajax and php [closed]

Answer 1

given select1 and select2 like this:

    X
    Y


    1
    2

then you can do something like this with jQuery:

$('#select1').on('change', function() {
    $.ajax({
        url: "test.html",
    }).done(function(response) {
        $('#select2').html(response);
});

This assumes your ajax call returns a string like

34

from your server sided file. If you return a json you have to decode it first, but this is the general gist of it. Take a look at the jQuery ajax() function