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The web space has many tools and resources, which are used on a daily, to keep websites running smoothly. Without these tools and resources, we wouldn’t be able to develop self-sustaining systems, which are scalable and are able to be changed to handle the growth that accompanies technology.
In today’s article we are going to talk about JavaScript in Drupal 8, and CSS in Drupal 8 so that you as a developer can add custom JavaScript or CSS code to a website and utilize the different libraries included in Drupal core.
It is important to know that using one of the many popular JavaScript libraries provided by Drupal core, is the way of adding custom JavaScript to a site. As a Drupal 8 developer, it is important to wrap our heads around the asset library system, because, our custom JavaScript code can be added to every page, based on the requirements we have for that page, by wrapping the JavaScript code in an asset library.
Passing configuration stored in the database to the front-end and implementing AJAX calls to a Drupal route can be easily achieved through the numerous Drupal-specific JavaScript libraries found in Drupal core.
jQuery, Backbone, Underscore and Modernizer are all part of Drupal as external projects. jQuery is the most common JavaScript library to developers, and the most used in Drupal core. AJAX, animation, event handling and DOM manipulations are easier to manage across all browsers due to the jQuery library’s simple API.
Widgets, animation, and effects with minimal code, can be provided using the jQuery UI, which contains interface elements. A simple in browser feature detection, is provided by the Modernizr asset library, which allow website developers, to customize a user’s experience according to what features they have available on their browsers.
Underscore.js and Backbone.js, are also very popular JavaScript library, Backbone allow users to add models and view to their application. Underscore on the other hand, provides an easier way for working with objects and arrays, through over 100 utility functions. Data objects such as the toolbar are represented, with Backbone models in Drupal 8. The user interface is described by using Backbone views, which are used by the CKEditor’s toolbar configuration and the Quick Edit module.
Alright now let’s talk just a little bit about CSS in Drupal 8, which can be included on a website, in different ways. Like JavaScript custom CSS must be loaded to Drupal 8 through an asset library, because these libraries contain one or more CSS assets. Developers can package the styling and functionality of components in a Drupal website, thanks to asset libraries.
Drupal sites are kept consistent when the asset library is used, to load CSS files, to a Drupal 8 site. The three steps that are followed to load a CSS/JS asset would be: first is to save the CSS or JS file, then the library needs to be defined, finally the library can be attached to a render array in a hook. A .library.yml file must be added to the root folder of the module, then inside of that file developers can define CSS and JS assets. Here is an example of the .library.yml file.
cuddly-slider:
version: 1.x
css:
layout:
css/cuddly-slider-layout.css: {}
theme:
css/cuddly-slider-theme.css: {}
js:
js/cuddly-slider.js: {}
Thank you for reading this article!!!
\Drupal\Component\Plugin\PluginManagerInterface,Implements all plugin managers, and this piece of code extends these three pieces of code, which are the basis for any new plugin manager.
\Drupal\Component\Plugin\Discovery\DiscoveryInterface, \Drupal\Component\Plugin\Factory\FactoryInterface and, \Drupal\Component\Plugin\Mapper\MapperInterface.The plugin.manager.* a piece of code is used to generate plugin manager services and from the service container, a copy of the plugin manager can be requested. Example:
$example_manager = \Drupal::service('plugin.manager.example');Once a developer has identified the plugin manager needed, to complete a task, then that developer has to start, by locating the name of the plugin manager service he/she needs. The controller will be the place where, a developer can inject their plugin manager services, and this is the Drupal way of doing things. The code below is a controller file, located under custom_module/src/Controller, it is very important that you get those names and file directory correct, for Drupal to recognize your controller and plugin.
<?php namespace Drupal\plugin_type_example\Controller; use Drupal\Core\Controller\ControllerBase; use Drupal\plugin_type_example\SandwichPluginManager; use Symfony\Component\DependencyInjection\ContainerInterface; /** * Controller for our example pages. */ class PluginTypeExampleController extends ControllerBase { /** * The sandwich plugin manager. * * We use this to get all of the sandwich plugins. * * @var \Drupal\plugin_type_example\SandwichPluginManager */ protected $sandwichManager; /** * Constructor. * * @param \Drupal\plugin_type_example\SandwichPluginManager $sandwich_manager * The sandwich plugin manager service. We're injecting this service so that * we can use it to access the sandwich plugins. */ public function __construct(SandwichPluginManager $sandwich_manager) { $this->sandwichManager = $sandwich_manager; } /** * {@inheritdoc} * * Override the parent method so that we can inject our sandwich plugin * manager service into the controller. * * For more about how dependency injection works read https://www.drupal.org/node/2133171 */ public static function create(ContainerInterface $container) { // Inject the plugin.manager.sandwich service that represents our plugin // manager as defined in the plugin_type_example.services.yml file. return new static($container->get('plugin.manager.sandwich')); } }All defined plugins have information that can aid our application development to move forward faster. All that information from defined plugins is available to developers when they can make calls to the getDefinitions method. Enabled modules, can be used to locate all plugin definitions of the type in question, through the discovery handler . When the discovery handler is not used to retrieve data, then the DefaultPluginManager is used to retrieve the data from the cache if the data is available there. A good example of is in the code below, watch how the definitions of a plugin can be obtained in the code.
// Get the list of all the sandwich plugins defined on the system from the // plugin manager. Note that at this point, what we have is *definitions* of // plugins, not the plugins themselves. $sandwich_plugin_definitions = $this->sandwichManager->getDefinitions(); // Let's output a list of the plugin definitions we now have. $items = array(); foreach ($sandwich_plugin_definitions as $sandwich_plugin_definition) { // Here we use various properties from the plugin definition. These values // are defined in the annotation at the top of the plugin class: see // \Drupal\plugin_type_example\Plugin\Sandwich\ExampleHamSandwich. $items[] = t("@id (calories: @calories, description: @description )", array( '@id' => $sandwich_plugin_definition['id'], '@calories' => $sandwich_plugin_definition['calories'], '@description' => $sandwich_plugin_definition['description'], )); } // Add our list to the render array. $build['plugin_definitions'] = array( '#theme' => 'item_list', '#title' => 'Sandwich plugin definitions', '#items' => $items, );When a list of plugin types is desired by a developer he/she may want to use the method above to accomplish this task. The unique ID of a plugin can be utilized in order to retrieve the definition of the plugin in question, calling the getDefinition($plugin_id) method. // If we want just a single plugin definition, we can use getDefinition(). // This requires us to know the ID of the plugin we want. This is set in the // annotation on the plugin class: see \Drupal\plugin_type_example\Plugin\Sandwich\ExampleHamSandwich. $ham_sandwich_plugin_definition = $this->sandwichManager->getDefinition('meatball_sandwich'); In order to instantiate and use an individual plugin object, the createInstance($plugin_id) method can be used. It is not good practice to instantiate a plugin object directly, instead, the plugin manager should be used to do so. Understanding how instances of a plugin are created requires that you see it in action, in the code below.
// To get an instance of a plugin, we call createInstance() on the plugin // manager, passing the ID of the plugin we want to load. Let's output a // list of the plugins by loading an instance of each plugin definition and // collecting the description from each. $items = array(); // The array of plugin definitions is keyed by plugin id, so we can just use // that to load our plugin instances. $sandwich_plugin_definitions = $this->sandwichManager->getDefinitions(); foreach ($sandwich_plugin_definitions as $plugin_id => $sandwich_plugin_definition) { // We now have a plugin instance. From here on it can be treated just as // any other object; have its properties examined, methods called, etc. $plugin = $this->sandwichManager->createInstance($plugin_id); $items[] = $plugin->description(); }All the code on this tutorial was taken from Drupalize.me. Thank you for reading this article!!!
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