Jquery .post with json problem

Jquery .post with json problem

Hi,
I am having a strange problem with my jquery code. I am making an ajax call to a php page and everything seems to work fine except the resulting JSON is coming as [Object][Object], [Object][Object] and so on. Here is my jquery code
  1. $.post('user/getPreviousInsertedTSData',{month:month},function(response){       
  2.       alert(response);
  3. },"json");
And here is my php code:
  1. $this->load->model('timesheets');
  2. $resSet['result'] = $this->timesheets->getUserReport($month,$user);
  3. $resStr =  json_encode($resSet['result']);
  4. log_message('error',json_encode($resSet['result']));
  5. echo $resStr;
I am using Codeigniter And in the log the JSON is coming fine, but in the alert box it's coming as [Object][Object], [Object][Object] and so on. Any ideas?