How to use ajax properly in Codeigniter?

Use ajax properly in Codeigniter

Paste In view

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

<script  src="<?php echo base_url(); ?>assets/js/custom.js" ></script>

<script>

$(document).ready(function(){

$(".ajax_bt").click(function(e) {

e.preventDefault();

    var person = $('#person').val();

    var phone = $('#phone').val();

    var email = $('#email').val();

    var password = $('#password').val();

//alert(person+''+''+phone+''+email+''+password);

  if(person != '' && phone != '' && email != '' && password != ''){

  

      $.ajax({

        url: "<?php echo base_url('index.php/Welcome/insert_data_with_ajax'); ?>",

        data: {

'person':person,

'phone':phone,

'email':email,

'password':password

}, // change this to send js object

        type: "post",

        success: function(data){

           //document.write(data); just do not use document.write

           console.log(data);

   $('#ajax_response').html(data);

   

        },

        error:function(data){

           //document.write(data); just do not use document.write

           console.log(data);

   $('#ajax_response').html('<p style="color:Red; margin:0px">Data not inserted...</p>');

   

        }

      });

       

    }

else{

$('#ajax_response').html('<p style="color:Red; margin:0px">Please fill all fields...</p>');

}

});

});

</script>

Paste In Controller

class Welcome extends CI_Controller {

 public function __construct()

    {

        parent::__construct();

        

        $this->load->library('session');

        $this->load->helper('html');

        $this->load->helper('url');

        $this->load->helper('form');

        $this->load->helper('file');

        $this->load->library('form_validation');

      

        $this->load->model('Customer_model');

       

    }

public function insert_data_with_ajax() {

$person = $this->input->post('person');

$phone = $this->input->post('phone');

$email = $this->input->post('email');

$password = $this->input->post('password');

$query = $this->Customer_model->register_user($person,$phone,$email,$password);

if($this->db->affected_rows() > 0){

 

echo 'Data inserted successfully';

 

}

else{  

echo 'Data Not inserted';

} 

die();

}

public function ajax()

{

if ($this->session->userdata('ID') == FALSE)

        {

            

redirect('register'); //if session is not there, redirect to login page

        }

$data['main_content']='ajax';

$this->load->view('template',$data);  

}

 

}

Paste In Model

class Customer_model extends CI_Model {

    public function __construct()

    {

        $this->load->database();

        $this->load->helper('url');

    }

function update_user($user_id,$name,$phone,$email,$password){

$data = array(

'name' => $name,

'phone' => $phone,

'email ' => $email,

'password ' => $password

);

$this->db->update('login_form', $data);

$this -> db -> where('ID', $user_id);

}

}