Your friend is opinionated. I work on a large TS project which has classes at its core. While it does make sense to use Classes at some locations, it's not alwa

Your friend is opinionated. I work on a large TS project which has classes at its core. While it does make sense to use Classes at some locations, it's not always an obvious choice. Writing and understanding Unit tests is painful in some places with classes. I keep business logic in classes and move the utility functions somewhere else(where I ensure functional paradigm). Writing Units Tests for such code is a breeze.