Change record status: 
Introduced in branch: 

In Drupal 7, drupal_add_css(), drupal_add_js() and drupal_add_library() could be used to add JS and CSS to a page. In Drupal 8, these functions have been removed. Instead, you must use #attached in a render array. #attached was already available in Drupal 7, and was widely used, but now it'll be the only way to attach assets.

Read the Adding stylesheets (CSS) and JavaScript (JS) to a Drupal 8 module documentation to find code samples.

Site builders, administrators, editors
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other updates done