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Core Dependencies

When to Use

When defining any JavaScript library - dependencies ensure required code loads first.

Decision

Core provides essential JavaScript libraries. Always declare exactly what your code needs - Drupal loads dependencies automatically and handles ordering.

Pattern

Common core dependencies: 

dependencies:
  - core/drupal          # Required for Drupal.behaviors, Drupal.t()
  - core/once            # Required for once() API
  - core/jquery          # Only if using jQuery functionality
  - core/drupal.ajax     # Required for AJAX features
  - core/drupal.announce # Required for screen reader announcements
  - core/drupal.debounce # Required for debounce() performance pattern
  - core/drupalSettings  # Automatic when using drupalSettings

Specialized dependencies: 

dependencies:
  - core/drupal.dialog        # Modal dialogs
  - core/drupal.dialog.ajax   # AJAX-loaded dialogs
  - core/drupal.dropbutton    # Admin interface dropbuttons
  - core/drupal.progress      # Progress indicators
  - core/drupal.states        # Form state management

Reference: View all core libraries at /core/core.libraries.yml

Common Mistakes

  • Including jQuery when not needed - WHY: Adds ~30KB weight, use vanilla JS instead
  • Missing drupal.ajax dependency - WHY: Drupal.ajax undefined, AJAX features break
  • Circular dependencies - WHY: Unpredictable load order, potential failures
  • Loading entire jQuery UI - WHY: Massive weight, only load specific components needed

See Also