Drupal 8: Including JavaScript files and libraries in your Drupal project.

basic_custom_module.libraries.yml

// Case 1: Basic library file with only JavaScript dependencies.
module_name.library_name:
  js:
    js/hello_world.js: {}
    
// Case 2: Typical file with CSS and JavaScript dependencies.
foo:
  version: 1.x
  css:
    theme: 
      css/foo.css: {}
  js:
    js/foo.js: {}

// Case 3: JavaScript library with jQuery dependency from Drupal Core. 
module_name.library_name:
  js: 
    js/foo.js: {}
  dependencies: 
    - core/jquery
   
// Case 4: Loading JavaScript libraries in head. 
js_library_for_header:
  header: true
  js:
    header.js: {}
js_library_for_footer:
  js:
    footer.js: {}
 
// Case 5: Adding external resources from your libraries.yml file.
backbone:
  remote: https://github.com/jashkenas/backbone
  version: "1.2.3"
  license:
    name: MIT
    url: https://github.com/jashkenas/backbone/blob/1.2.3/LICENSE
    gpl-compatible: true
  js:
    assets/vendor/backbone/backbone-min.js: { weight: -19, minified: true }
  dependencies:
    - core/underscore
    
 // Case 6: Declaring dependencies
 js_library_hide_show:
  js:
    js/my_custom_javascript_library.js: {}
  dependencies:
    - core/jquery
    
// Case 7: Fully external library
angular.angularjs:
  remote: https://github.com/angular/angular.js
  version: 1.4.4
  license:
    name: MIT
    url: https://github.com/angular/angular.js/blob/master/LICENSE
    gpl-compatible: true
  js:
    https://ajax.googleapis.com/ajax/libs/angularjs/1.4.4/angular.min.js: { type: external, minified: true }