hook_js_alter(&$javascript, \Drupal\Core\Asset\AttachedAssetsInterface $assets) Perform necessary alterations
hook_theme_registry_alter(&$theme_registry) Alter the theme registry information returned from
hook_library_info_build() Add dynamic library definitions. Modules may implement
hook_render_template($template_file, $variables) Render a template using the theme engine.
hook_form_system_theme_settings_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state) Allow themes
hook_preprocess(&$variables, $hook) Preprocess theme variables for templates. This
hook_page_attachments_alter(array &$attachments) Alter attachments (typically assets) to a page before
hook_element_info_alter(array &$info) Alter the element type information returned from modules
Overview of the Theme system and Render API. The main purpose of Drupal's Theme system is to give themes complete control over the appearance
hook_page_attachments(array &$attachments) Add attachments (typically assets) to a page before it is rendered
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