Add custom class to the elements of a View

Example:

/**

 * Add classes to a view

 * @param $vars

 */

function MYTHEME_preprocess_views_view_list(&$vars) {

    if ($vars['view']->name == 'article') {

        $view = $vars['view'];

        foreach ($view->result as $row_index => $result) {

            $val1 = strlen($result->field_body[0]['rendered']['#markup']);

            $val2 = strlen($result->field_body[0]['raw']['safe_value']);

                $vars['classes_array'][$row_index] .= ' my-class';

        }

    }

}

Note : Tested in Drupal 7 but not Drupal 8