// Prevent empty search via jQuery 
// By Amirhosseinhpv [https://hpv.im/] 
// Following snippet is applied for WordPress 2020 theme's header search 

(function($) {
  $(document).ready(function() {
    $(document).on("submit", "form.search-form", function(e) {
      if ($.trim($('form.search-form input.search-field').val()) == '') {
        e.preventDefault();
        return false;
      }
    });
  });
})(jQuery);

// Prevent empty search in WordPress
// By Amirhosseinhpv [https://hpv.im/] 

add_action('pre_get_posts', 'search_redirect');

function search_redirect($query)
{
    if (!is_admin() && $query->is_main_query()) {
        if ($query->is_search) {
            if (empty(trim(get_query_var("s")))) {
                  wp_redirect(home_url());
                  exit; 
            } 
        } 
    } 
}