Learn TypeScript 3 by Building Web Applications

Interfaces versus classes

So now that you have seen both classes and interfaces/custom types, one question that you might ask yourself is how to choose between the two? When does it make sense to create one rather than the other?

As with many design choices, the general answer is it depends, but here are a few points that you should consider to help you decide.

Consider defining a class when you need to do any of the following:

• You need to create multiple new instances at different locations of your code base. Using a class, you can centralize the logic for doing so and adapt it easily in one place.
• You need to validate things when creating new instances (for example, ensure that a date has been provided, is valid, and so on). With a class, ...