$(function(){
    $("select#city").change(function(){
        $.getJSON("/ajax.php", {Method: 'Locations', cityId: $(this).val()}, function(j){
            var options = '<option value="">Select...</option>';
            for (var i = 0; i < j.length; i++) {
                options += '<option value="' + j[i].locationId + '">' + j[i].locationName + '</option>';
            }
            $("#location").html(options);
            $('#location option:first').attr('selected', 'selected');
        });
    });
});