How do I use drupal_add_library(), drupal_add_css() and drupal_add_js() in Drupal 8?

I am porting a module that uses those functions. I am following what reported in this post, which says these functions have been removed in favor of #attached, but I am not able to attach these files to my configuration page.

The error I am getting is the following:

Uncaught PHP Exception LogicException: "You are not allowed to use js in #attached"

How do I attach CSS and JavaScript to a page?

  • You simply don't use those functions, since they don't exist in Drupal 8, nor do you use the renamed functions. What exactly you don't understand? #attached was already used from Drupal 7.
    – apaderno
    Commented May 31, 2015 at 17:45
  • @kiamlaluno: Using D8 version of the functions is throwing me an Error which says "Uncaught PHP Exception LogicException: "You are not allowed to use js in #attached"" So I am confused how to use #attached for including js and css.. Commented May 31, 2015 at 17:50
  • You're not alone: drupal.org/node/2391025
    – Clive
    Commented May 31, 2015 at 18:31
  • 1
    @Clive inline JS is something else, I don't think that's the question. The question mentiones "files" :)
    – Berdir
    Commented May 31, 2015 at 19:43

2 Answers 2


Drupal_add_js() and Drupal_add_css() are quite simple to write in Drupal 8.

We basically create a module_name.libraries.ymlfile having list of all the jss and css that we wish to use.

An example of which is

name_of_the_key: // This would basically work as a key for you.
  version: 1.x
    js/name_of_your_js_file.js: {}  // Name of your js file
  dependencies:  // Adding dependencies if you have any.
    - core/jquery
    - core/drupalSettings
    css/name_of_the_css_file.css: {} // Name of your css file.

This would basically add all the files but would not attach these files to your page/form.

So in order to attach the js and css to your page/form, you simply replace



$form['#attached']['library'][] = 'name_of your_module/name_of_the_key'; // Name of the key would be the key that you have defined in module_name.libraries.yml file.

So if your module uses different js and css file at different points in a forms/pages you could define n number of keys in your libraries.yml file and use it accordingly.

Source: https://www.drupal.org/node/2274843 and guidance form AjitS.


You can no longer add standalone CSS or JS files, you need to make everything a library.

Unless you have something that's dynamic, it's a bit of work to define it, but easy enough.

That change notice is outdated, common problem. It however does have a bold note that links to change records for adding javscript settings (not the same as inline JS as it is static and only conditions definitions/configuration).

There are also some pretty extensive docs available here: Adding stylesheets (CSS) and JavaScript (JS) to a Drupal 8 module.

If you're building javascript dynamically and need to add that, then that's a bit more complicated. You can for example add it as a standalone head element yourself, but then you won't get things like weights/dependencies. That's also documented on the link above, but the recommended approach for that is to write a JS file and then trigger different behavior through javascript settings.

  • Probably worth mentioning drupal.org/list-changes as an important resource?
    – AjitS
    Commented May 31, 2015 at 20:22
  • 2
    @AjitS The question already links to a change record, so I assume that resource is known. But yes, that is an important/useful resource. And unlike many other things, it's actually more useful to search there directly instead of google as you get most recent matches first and not old stuff.
    – Berdir
    Commented May 31, 2015 at 21:22

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