[Wouter60]

You don't need a hidden field. You can "inject" a php variable into Javascript code.

Example:

Code:

$('#some_button').click(function(){
  var url = "<?= site_url('groups/anotherfunction/' . $page_id);?>";
  $.post( url )
  .done(function(data) {
     $('#some_element').html(data);
  });
});

In the controller, load the view and put it in a variable:

PHP Code:

$dynamic_html = $this->load->view('group/anotherFunction',NULL,TRUE);
echo $dynamic_html; 


The 3rd argument of $this->load->view() will return the value.
The echo in the controller function will return the result to the Ajax call.
Maybe loading the view as usual will work as well, but I didn't test that.