特定のformにJavaScriptを紐付ける方法

MODULE/MODULE.libraries.yml

xxx.form:
  js:
    js/MODULE.js: {}
  dependencies:
    - core/jquery
    - core/drupal

MODULE/MODULE.module

function MODULE_form_FORMID_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  $form['any']['#attached']['library'][] = 'MODULE/xxx.form';
}