JQuery从回调函数发布数据

I want to post data from a callback function in jQuery:

// in my "index.php"
$.post('users.php', { user : the_users_name } ,function(data) {
    $('body').html(data)
}

In the users.php I want to post data to another script without loading the users.php like below:

$.post('users2.php', { date_of_birth : $(".d_of_b_div").val() }      

Now since users.php is only called as a result of $.post in index.php, it doesn't post data to users2.php.

How can I solve this problem? Or what am I missing out?

In your index.php

$.ajax({
  url: 'users.php',
  method: 'post',
  data: { user : the_users_name },
  success: function(data) {
    $('body').html(data)
  },
  complete: function() {
    // use complete callback to call users2.php
    // this is only called after success and error callbacks are executed
    $.post('users2.php', { date_of_birth : $(".d_of_b_div").val() });
  }
});