I have a search field. There is no issue with the search if I enter anything on this and click on button then it’s redirecting on the page where I can get my search result.

What I am doing is, I have to display the category dropdown auto search list when the user enters any text in the search field. I found one plugin (https://wordpress.org/plugins/ajax-search-lite/) also demo here (https://lite.ajaxsearchpro.com/). I am trying to do the same but I can’t use the plugin.

I need to know what query I have to use on the ajax to get the output?

Form code

function search_form($atts) { 
     $form = '<section class="universalSearch"><div class="search search-form"><form role="search" method="get" action="' . home_url( '/' ) . '" >
    <label class="screen-reader-text" for="s">SEARCH</label>
     <input type="search" class="search-field universalSearchField" value="' . get_search_query() . '" name="s"  placeholder="Search" />
     <input type="submit" id="searchsubmit" class="search-submit" value="'. esc_attr__('Go', 'domain') .'" />
     </form></div></section>
     <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
     <script>
          (function($) {  // ready handler
$(".universalSearchField").keypress(function() {
      $.post("/wp-admin/admin-ajax.php", {"action":"universalSearchlist"}, function(response) {
          $(".universalSearch").append(response);
        console.log( response );
      });
    });
    })(jQuery);
    </script>';
    
     return $form;
}

add_shortcode( 'get_search_form', 'search_form');

AjAX code

add_action('wp_ajax_universalSearchlist','universalSearch');
add_action('wp_ajax_nopriv_universalSearchlist','universalSearch');
function universalSearch(){
    $data='';
    $args = array(
     's' => $_REQUEST[ 'universalSearchlist' ],
     'cat' => 'category'
);
    
    $the_query = new WP_Query( $args );
    foreach ($the_query->posts as $post) {
        var_dump($post);
    }
    

    //endif;
    //die();
    return $data;
    
}