Multilingual in Javascript

The Drupal core javascript library (core/drupal) ships with two functions to support multilingual in Javascript. Drupal.t() and Drupal.formatPlural() are two functions available, that work just like their PHP equivalents:

Drupal.t()

PHP: ?

var close = Drupal.t('Close');
var nodesOfType = Drupal.t('Showing nodes of @type', {@type: nodeType});

Drupal.formatPlural()

PHP: \Drupal\Core\StringTranslation\TranslationInterface::formatPlural()

var nodesCount = Drupal.formatPlural(count, '1 node', '@count nodes');
var nodesCountOfType = Drupal.formatPlural(count, '1 node of @type', '@count nodes of @type', {@type: nodeType});