Specific page with ajax filter

Question

I made a function that filters wordpress categories

functions.php

   function load_scripts() {

  wp_enqueue_script('ajax', get_template_directory_uri() . '/vendor/jquery/main.js', array('jquery'), NULL, true);

  wp_localize_script('ajax' , 'wp_ajax',
      array('ajax_url' => admin_url('admin-ajax.php'))
      );

}

add_action( 'wp_enqueue_scripts', 'load_scripts');
add_action( 'wp_ajax_nopriv_filter', 'filter_ajax' );
add_action( 'wp_ajax_filter', 'filter_ajax' );

function filter_ajax() {
  
$category = $_POST['category'];

if(isset($_POST['pageslug']) && $_POST['pageslug'] === 'faq'){
      $cat__in = 10;
      print_r(  $_POST );
      echo "FAQ";

  } else{
    $cat__in = 4;
    print_r(  $_POST );
    echo "Products";
  }
  
$args = array(
'post_type' => 'post',
'posts_per_page' => 50,
'category__in' => $cat__in,
);

if(isset($category)) {

  $args['category__in'] = array($category);
}


      $query = new WP_Query($args);

      if($query->have_posts()) :
          while($query->have_posts()) : $query->the_post();
              the_title('<h2>', '</h2>');
              the_content('<p>', '</p>');
          endwhile;
      endif;
          wp_reset_postdata(); 
  die();
}

I want the displayed categories to be different on the "FAQ" and "PRODUCTS" pages, so I used

if(isset($_POST['pageslug']) && $_POST['pageslug'] === 'faq'){
      $cat__in = 10;
  } else{
    $cat__in = 4;
  }

but since I'm using ajax, the function doesn't recognize pages.

main.js

  (function($){
    $(document).ready(function(){
        $(document).on('click', '.js-filter-item > a', function(e){
            e.preventDefault();

            var category = $(this).data('category');

            $.ajax({
                url:wp_ajax.ajax_url,
        data: { 
          action: 'filter', 
          category: category, 
          id: location.pathname.replace(/\//g,'') 
        },
                type: 'post',
                success: function(result) {
                    $('.js-filter').html(result);
                },
                error: function(result) {
                    console.warn(result);
                }
            });
        });
    });
})(jQuery);

What am I doing wrong? I tried that way too, but it doesn't work either functions.php

   if (is_page('faq') ) {
        $cat__in = 10;
    } else {
        $cat__in = 6;
    }