A framework is a set of code that provides support for application development by offering templates, components and examples. Royale provides its own framework for making simple, small and fast applications, but also offers support for using other popular JavaScript frameworks.
Why would you use a third-party framework with Royale? Because you like the look and feel of that framework's user interface components but want to use ActionScript to handle the business logic and/or use MXML to set up the UI.
Royale supports (to varying degrees):
Material Design Lite{:target=‘_blank’} Most, if not all, components are available.
JQuery UI{:target=‘_blank’} Only a few components are available. Volunteers are needed to support more components. Note that this does not mean that you write actual JQuery queries in your application source code; it just means that you can use the user interface controls to get the same user experience as JQuery apps offer.
CreateJS{:target=‘_blank’} Only a few components are available. Volunteers are needed to support more components.
Many other JavaScript frameworks could be made to work with Royale if they support dynamic instantiation of components. All it takes is volunteers to make it happen.