The addition of the asset library system in Drupal 8, while new, is quite well established. There may be emerging best practices regarding how to split up and structure your custom libraries, but the overall concepts are unlikely to change.
- Use Server-Side Settings with drupalSettings
- Backbone.js in a Theme or Module, Underscore.js in a Theme or Module, and Modernizer.js in a Theme or Module
- What's New in Drupal 8: Theming