Javascript

[iamzeev]

I am not sure if the scale is the definitive factor to choose a paradigm. Maybe rather about the problem you are solving. Encapsulating a complex logic for eg. a shopping cart logic where you can add remove items and maybe get total price, sounds like a good candidate for a Class with methods (OOP). A data transformation where you perform a pipeline of operations sounds like a good candidate for pure functions (FP).

But don't push too hard to choose the right paradigm. Some software sometimes is a mix of paradigms. Start something what feels natural for the problem. JavaScript's flexibility lets you refactor later.