We should conquer the frameworks, instead of being slaves of the frameworks, whether it is Angular, React, or something.

We should develop our core with only features available in the JavaScript/TypeScript language. For example, instead of directly using dependency injection, we should manually write a factory function. If we want to integrate the DI of, say, Angular, we can wrap around it a layer of injectable classes. But keep in mind that the core must not use the functionalities available only in the framework.

This will ease your pain when upgrading frameworks, sharing code between projects on the same subject but using different frameworks (e.g. the web version of this website is built with Angular, while the app is built with React Native).