Lately, I've been using almost exclusively interfaces and custom types in my applications.

I've written about this here: https://medium.com/javascript-in-plain-english/why-you-should-generally-prefer-typescript-interfaces-and-custom-types-over-classes-d145814218ce

There are things that I haven't discussed there though, like how to deal with validation and decorators, which can only be added to classes and actually requires the introduction of some classes.

For the most part though, classes are not that interesting. I guess that BDD aficionados will not agree, but I prefer to manipulate pure immutable data.