[jQuery] how can I call php function in jquery ?

[jQuery] how can I call php function in jquery ?


I have in PHP file ajax.php:
class Data
{
    public function __construct()
    {
        ....................
    }
    public function select($idl)
    {
        ....................
    }
    public function delete($id)
    {
        .....................
    }
}
My jquery function looks now:
function deleteComment(id)
{
    $.post("ajax.php",
        {
        },
        function(data) {
...........
        }
    );
}
How can I in function deleteComment(id) call php function delete($id)
from file ajax.php ?