Introduction

Drupal 8 brought many changes with regard to the frontend. It is now focused on mobile-first responsive design. Frontend performance has been given a high priority, unlike in the previous versions of Drupal. There is a new asset management system based on libraries that will deliver only the minimum required assets for a page that comes with Drupal 8.

In Drupal 8, we have a new feature, the Twig templating engine, that replaces the previously used PHPTemplate engine. Twig is part of the large PHP community and embraces more of Drupal 8's made elsewhere initiative. Drupal 7 supported libraries to define JavaScript and CSS resources. However, it was very rudimentary and did not support the concept of library dependencies.

There are two modules provided by the Drupal core that implement the responsive design with server-side components. The Breakpoint module provides a representation of media queries that modules can utilize. The Responsive Image module implements the HTML5 picture...