post ajax data to PHP and return data

 $.ajax({            type: "POST",            data: {data:the_id},            url: "http://localhost/test/index.php/data/count_votes",            success: function(data){               //data will contain the vote count echoed by the controller i.e.                   "yourVoteCount"              //then append the result where ever you want like              $("span#votes_number").html(data); //data will be containing the vote count which you have echoed from the controller                }            });

in the controller

$data = $_POST['data'];  //$data will contain the_id//do some processingecho "yourVoteCount";

Clarification

i think you are confusing

{data:the_id}

with

success:function(data){

both the data are different for your own clarity sake you can modify it as

success:function(vote_count){$(span#someId).html(vote_count);

For the JS, try

data: {id: the_id}...success: function(data) {        alert('the server returned ' + data;    }

and

$the_id = intval($_POST['id']);

in PHP

So what does count_votes look like? Is it a script? Anything that you want to get back from an ajax call can be retrieved using a simple echo (of course you could use JSON or xml, but for this simple example you would just need to output something in count_votes.php like:

$id = $_POST['id'];function getVotes($id){    // call your database here    $query = ("SELECT votes FROM poll WHERE ID = $id");    $result = @mysql_query($query);    $row = mysql_fetch_row($result);    return $row->votes;}$votes = getVotes($id);echo $votes;

This is just pseudocode, but should give you the idea. What ever you echo from count_votes will be what is returned to "data" in your ajax call.