Global Libraries (e.g. jQuery)

There are some instances in which a library should be available to all components, i.e. "global."

jQuery

Use the following steps to make jQuery available to your component javascript files and to use additional libraries that require jQuery.

Add jQuery Library

yarn add jquery

Add jQuery to Storybook Config

Create a /.storybook/jquery-global.js file and add the following:

import jquery from 'jquery';
global.jQuery = jquery;
global.$ = jquery;

Import this file in ./storybook/preview.js:

   ...
   import './_drupal.js';
+  import './jquery-global.js';

This ensures that jQuery is loaded before other libraries. See this explanation for details.

Add jQuery as a Global in Webpack

Add the following to /.storybook/webpack.config.js:

   loader: 'eslint-loader',
   options: {
     cache: true,
+      globals: [
+        'jQuery'
+      ],
   },

Add jQuery as a Global to ESLint config

Add the following to .eslintrc.yml:

    describe: true
    Drupal: true
+   jQuery: true
  parser: babel-eslint

Example: Use jQuery in a Component

The following example will cause the error status message to blink.

Create JS file

Create components/02-molecules/status/status.js and add the following:

($ => {
  Drupal.behaviors.status = {
    attach() {
      setInterval(() => {
        $('.status--error').fadeToggle();
      }, 500);
    },
  };
})(jQuery);

Update the Status Story

Add the new JS file to the components/02-molecules/status/status.stories.js and include the DrupalBehaviors effect:

  import React from 'react';
+ import { useEffect } from '@storybook/client-api';
​
  import status from './status.twig';
​
  import statusData from './status.yml';
​
+ import './status';
+
  /**
   * Storybook Definition.
   */
  export default { title: 'Molecules/Status' };
​
- export const statusExamples = () => (
-   <div dangerouslySetInnerHTML={{ __html: status(statusData) }} />
- );
+ export const statusExamples = () => {
+   useEffect(() => Drupal.attachBehaviors(), []);
+   return <div dangerouslySetInnerHTML={{ __html: status(statusData) }} />;
+ };

Now if you run the storybook yarn develop you should see a blinking error message in the status molecule.

Add JS File to Theme Library and Load in the Template

Add the JS file to the theme library by editing MY_THEME.libraries.yml:

+
+ status:
+   js:
+     dist/js/02-molecules/status/status.js: {}
+   dependencies:
+     - core/drupal
+     - core/jquery

Make sure to include the drupal and jquery core libraries as dependencies. They will both be loaded before your JS file in Drupal.

The library then needs to be loaded in the component twig template. In this case edit components/02-molecules/status/status.stories.twig and add:

+ {{ attach_library('THEME_NAME/status') }}

Add jQuery Once

To include jQuery once() add it to your project:

yarn add jquery-once

Add add it to your the /.storybook/config.js file:

  import './jquery-global.js';
+ import once from 'jquery-once';

Libraries for Individual Components

There are a couple of strategies for loading individual libraries.

Add with Yarn

Add an external library using yarn by adding it to your project yarn add LIBRARY and then importing where needed.

Load Library from an External URL

External libraries, for example from a CDN, can be loaded with Storybook External Links. Install, yarn add storybook-external-links and add to the /.storybook/config.js or an individual story file:

+ import withExternalLinks from 'storybook-external-links';
+ const url = '//[URL TO LIBRARY]';
+ const externalLinkDecorator = withExternalLinks(url);
+ addDecorator(externalLinkDecorator);