$this->t('Add files'), '#type' => 'checkbox', '#default_value' => FALSE, ]; $form['submit'] = [ '#type' => 'submit', '#value' => $this->t('Submit'), '#ajax' => [ 'wrapper' => 'ajax-forms-test-lazy-load-ajax-wrapper', 'callback' => 'ajax_forms_test_lazy_load_form_ajax', ], '#prefix' => '

', ]; return $form; } /** * {@inheritdoc} */ public function submitForm(array &$form, FormStateInterface $form_state) { $form_state->setRebuild(); } }