code: public function enableOptionsFilteringByKeywords($minCharsToInitFiltering = 1) {
          $this->enableOptionsFilteringByKeywords = true;
          $this->minCharsRequiredToInitOptionsFiltering = (int)$minCharsToInitFiltering;
          return $this;
      }
docs: Allows autocomplete functionality (search by keywords) for <select> inputs using options loader
  @param int $minCharsToInitFiltering - minimum characters required to initiate ajax request
  @return $this