JavasScript from custom module not detected
Drupal uses a high-level principle: assets (CSS or JS) are still only
  loaded if you tell Drupal it should load them. Drupal does not load
  all assets (CSS/JS) on all pages, because this is bad for front-end
  performance.


You need to inform Drupal to attach your library to the page.

In your case, you can use hook_form_alter and check the $form_id or hook_form_FORM_ID_alter for a single case and add this:

$form['#attached']['library'][] = 'mymodule/nodeEditForm';

Then clear the cache. Search the core folder for $form['#attached'] for more examples. You should then see your js file listed in the source of the page as well as console log output.