breakpointManager example

  public static function preRenderToolbar($element) {
    // Get the configured breakpoints to switch from vertical to horizontal     // toolbar presentation.     $breakpoints = static::breakpointManager()->getBreakpointsByGroup('toolbar');
    if (!empty($breakpoints)) {
      $media_queries = [];
      foreach ($breakpoints as $id => $breakpoint) {
        $media_queries[$id] = $breakpoint->getMediaQuery();
      }

      $element['#attached']['drupalSettings']['toolbar']['breakpoints'] = $media_queries;
    }

    $module_handler = static::moduleHandler();
    // Get toolbar items from all modules that implement hook_toolbar().