How to destroy session with browser closing in codeigniter

You can use javascript and asynchron request. When you close the window, the handler of window.onunload is called

var unloadHandler = function(e){
        //here ajax request to close session
  };
window.unload = unloadHandler;

To solve the problem of redirection, php side you can use a counter

  class someController  extends Controller {

   public function methodWithRedirection(){

        $this->session->set_userdata('isRedirection', 1);
        //here you can redirect  
   }
}
class homeController extends Controller{
   public function closeConnection(){
        $this->load->library('session');
        if($this->session->userdata('isRedirection')!== 1){
            //destroy session
         }
      }
   }  

Have a look at this, and see if this helps.

https://github.com/EllisLab/CodeIgniter/wiki/PK-Session

Edit the config.php file and set sess_expire_on_close to true.

e.g

$config['sess_expire_on_close'] = TRUE;

Add a logout button.

Have that button destroy the session with CI's built in destroy function.

$this->session->sess_destroy();