my-theme/js/my-script.js

my-library:
  js:
    js/my-script.js: {}

name: my-theme
type: theme
description: my theme
package: other
core: 8.x
libraries:
  - my-theme/global-effects
  - my-theme/my-library

base theme: stable

function mytheme_page_attachments_alter(&$page){
  $path = $current_path = Drupal::service('path.current')->getPath();
  if($path == '/node') {
    $page['#attached']['library'][] = 'my-theme/my-library';
  }
}

function mytheme_preprocess_page(&$variables){
  if ($variables['is_front'] == TRUE) {
    $variables['#attached']['library'][] = 'my-theme/my-library';
  }
}

{% if node.id == 1 %}
  {{ attach_library('my-theme/my-library') }}
{% endif %}