Attach an Asset Library for Drupal 8, Drupal 9

Last updated July 12, 2019
Theming8.9.x/9.0.x

Once you've defined an asset library you'll need to tell Drupal when you want to add the CSS and JavaScript that it includes to the page. Ideally you'll do so in a way that allows Drupal to only add the corresponding assets on pages where they are needed.

You can attach a library to all pages, a subset of pages, or to elements in a render array. This allows you to have some assets that are global, and others that get loaded on an as-needed basis. To attach a library you'll need to know both its name and prefix, and then use one of the techniques outlined below to let Drupal know when to include it.

In this tutorial, we'll look at attaching asset libraries:

  • Globally, via your THEMENAME.info.yml file
  • Conditionally, via a preprocess function using the #attached render array property
  • Inside of a Twig template file

By the end of this tutorial you should be able to attach asset libraries in various different ways depending on your use case.