Add javascript and stylesheet to module

What is?

https://www.drupal.org/node/2274843

CSS and JavaScript files work together to provide a style and functionality.

How to use?

1. Save the CSS or JS to a file Javascript file for module/CSS file for module
2. Define a library, which can contain both CSS and JS files Define a library for module
3. Now you can attach the library in different ways:
   • Attach globally
   • Attach to a specific page

   • Attach in a twig template