javascript - 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'
            )));