Tos Web Developer - Drupal Developer And Web Developer Helping Blog

Libraries have the ability to specify other libraries as dependencies. This allows Drupal to provide a minimum footprint on the fronted performance.

jQuery is only loaded if a JavaScript library specifies it as a dependency.
Refer to https://www.drupal.org/node/1541860


Here's an example from the Quick Edit module's libraries.yml file:

 quickedit:  
  version: VERSION  
  js:  
  ...  
  css:  
  ...  
  dependencies:  
  - core/jquery  
  - core/jquery.once  
  - core/underscore  
  - core/backbone  
  - core/jquery.form  
  - core/jquery.ui.position  
  - core/drupal  
  - core/drupal.displace  
  - core/drupal.form  
  - core/drupal.ajax  
  - core/drupal.debounce  
  - core/drupalSettings  
 - core/drupal.dialog  

The Quick Edit module defines jQuery, the jQuery Once plugin, Underscore, and Backbone, and selects other defined libraries as dependencies. Drupal will ensure that these are present whenever the quickedit/quickedit library is attached to a page.

A complete list of the default libraries provided by Drupal core can be found in the core. libraries.yml, which is in core/core.libraries.yml.