Codeigniter - How to access user defined function using ajax?

1) Create method in controller 2) Call Same library function captch_refresh in controller and return data from library function. 3) Send response from controller's method

Ajax Call Url:

// Controller Code
class Login extends MY_Controller {

public function captcha_refresh() {
   // load library
   $this->load->library('captcha_lib');
   // call library function
   echo $this->captcha_lib->captcha_refresh();
   exit(); 
}


// Make Library method
class Captcha_lib {
public function captcha_refresh(){
    $CI =& get_instance();

    $values = array(
    'word' => '',
    'word_length' => 8,
    'img_path' => './hrms_assets/captcha_img/',
    'img_url' => base_url() .'hrms_assets/captcha_img/',
    'font_path' => base_url() . 'system/fonts/texb.ttf',
    'img_width' => '150',
    'img_height' => 50,
    'expiration' => 3600
    );
    $data = create_captcha($values);
    $CI->session->userdata['captchaWord'] = $data['word'];
    return $data['image'];
}

}

// Jquery Code

$(document).ready(function() {
    $("a.refresh").click(function() {
    jQuery.ajax({
    type: "POST",
    url: "<?php echo base_url('login/captcha_refresh'); ?>",
    success: function(res) {
    if (res)
    {
    jQuery("span.image").html(res);
    }
    }
    });
    });
    });

Try this one:

$(document).ready(function() {
            $("a.refresh").click(function() {
               jQuery.ajax({
                 type: "POST",
                 url: "<?php echo APPPATH; ?>" + "libraries/Captcha_lib/captcha_refresh",
                 success: function(res) {
                    if (res)
                    {
                      jQuery("span.image").html(res);
                    }
                 }
               });
             });
            });

Or Create a controller & call you library over there to execute you function.

class Welcome extends CI_Controller {

    public function index()
    {
        $this->load->libraray('captcha_lib');
        echo $this->captcha_lib->captcha_refresh();
    }
}

After this your ajax url should be like this: url: "<?php echo base_url('welcome/index'); ?>",

You are doing in wrong way , your code :-

    jQuery.ajax({

        type: "POST",
        url: "<?php echo base_url(); ?>" + "application/libraries/Captcha_lib/captcha_refresh",
        success: function(res) {

             .....

In this your URL will be like this "http://your-site/application/libraries/Captcha_lib/captcha_refresh" . it means you will make a request on this URL and it will give response to you only if :-

• You uses URL Rewrite to convert this into an actual URL
• This is original URL

But in your case none is true . Your actual URL is "http://my-site/application/libraries/Captcha_lib.php" and captcha_refresh is a function inside the file Captcha_lib.php . So it is not going to execute by calling Captcha_lib.php file only . Its like that you have a file with class based but there are no main() function .

So better to use MVC (Model View Controller) technique. You can create a controller and load the library in the controller like this :-

 <?php 

 # application/controllers/HandleMe.php

 class HandleMe extends CI_Controller
 {

      function index()
      {
            $this->load->library('Captcha_lib');
            echo $this->captcha_lib->captcha_refresh();
      }
 }

And your javascript code should be

   jQuery.ajax({
    type: "POST",
    url: "<?php echo base_url(); ?>" + "index.php/HandleMe",
    .....