Codeigniter 4 ajax post results in 404 error

I am trying to handle a form submit using the JQuery ajax function on localhost xampp. However, the following always results in a 404 page not found error:

Code:

$(document).on("click", ".iconsTop .iconst", function (e) {
    var idfilter = $(this).attr("id");;
    $.ajax({
      type: "POST",
      dataType: "text",
      url: "filter",
      data: { filter_id:idfilter },
      cache: false,
      success: function (data) {
        $('.maincontact').empty().append(data);
      }
    });
  });

Controller:

PHP Code:

class App_home extends BaseController
{
    public function filter()
    {
        echo 'ok';
    }
} 


Router

PHP Code:

use CodeIgniter\Router\RouteCollection;
$routes->setAutoRoute(true);
$routes->get('filter', 'App_home::filter'); 


After submitting the form, I always get the following error in Google Chrome's page inspector:

jquery-3.7.1.min.js:2 POST http://localhost/app/public/filter 404 (Not Found)

404 Controller or its method is not found: Filter::index

Why there is public in your url ? 
Have you set base_url with public ?

Can you try to change 

$routes->get('filter', 'App_home::filter');

to

$routes->get('/filter', 'App_home::filter');

Why there is public in your url ? 
Have you set base_url with public ?

Can you try to change 

$routes->get('filter', 'App_home::filter');

to

$routes->get('/filter', 'App_home::filter');

Should I delete public?

My baseurl is as:

Code:

public string $baseURL = 'http://localhost:80/';

I change to `$routes->get('/filter', 'App_home::filter');` but there is the same error

Well, I don't use setAutoRoute(true). So, I manually set my routes not only for $routes->gets but also for $routes->posts. Maybe this could be your problem too ??

Check here on documentation. You can also use match option for both get and post for the same url

Did you try like this?

PHP Code:

$.ajax({
    url: `<?= route_to('filter') ?>`, 


What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )