CodeIgniter - How to return Json response from controller

Question

How do I return response from the controller back to the Jquery Javascript?

Javascript

$('.signinform').submit(function() {     $(this).ajaxSubmit({         type : "POST",        url: 'index.php/user/signin', // target element(s) to be updated with server response         cache : false,        success : onSuccessRegistered,        error: onFailRegistered    });            return false;  });  

Data is returned null (blank)!

function onSuccessRegistered(data){     alert(data); }; 

Controller -

public function signin() {     $arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);         echo json_encode( $arr ); } 

Answer 1

return $this->output             ->set_content_type('application/json')             ->set_status_header(500)             ->set_output(json_encode(array(                     'text' => 'Error 500',                     'type' => 'danger'             )));